release: 4.4.0

Merge pull request #725 from Zerotask/add-hint-corresponding-readme
chore(watch): add hint for the exercises README.md
2025-12-26 00:11:49 +02:00 · 2021-04-24 11:57:00 +02:00 · 2021-04-24 11:46:25 +02:00 · 2021-04-24 11:45:56 +02:00 · 2021-04-24 11:45:37 +02:00 · 2021-04-23 20:28:55 +02:00
89 changed files with 3724 additions and 1333 deletions
--- a/.all-contributorsrc
+++ b/.all-contributorsrc
@@ -0,0 +1,849 @@
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+      "name": "Jean-Francois Chevrette",
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+      "profile": "https://github.com/jfchevrette",
+      "contributions": [
+        "content",
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+    },
+    {
+      "login": "jbaber",
+      "name": "John Baber-Lucero",
+      "avatar_url": "https://avatars.githubusercontent.com/u/1908117?v=4",
+      "profile": "https://github.com/jbaber",
+      "contributions": [
+        "content"
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+    {
+      "login": "tal-zvon",
+      "name": "Tal",
+      "avatar_url": "https://avatars.githubusercontent.com/u/3195851?v=4",
+      "profile": "https://github.com/tal-zvon",
+      "contributions": [
+        "content"
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+    {
+      "login": "apogeeoak",
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+      "avatar_url": "https://avatars.githubusercontent.com/u/59737221?v=4",
+      "profile": "https://github.com/apogeeoak",
+      "contributions": [
+        "content",
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+    },
+    {
+      "login": "Crell",
+      "name": "Larry Garfield",
+      "avatar_url": "https://avatars.githubusercontent.com/u/254863?v=4",
+      "profile": "http://www.garfieldtech.com/",
+      "contributions": [
+        "content"
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+    {
+      "login": "circumspect",
+      "name": "circumspect",
+      "avatar_url": "https://avatars.githubusercontent.com/u/40770208?v=4",
+      "profile": "https://github.com/circumspect",
+      "contributions": [
+        "content"
+      ]
+    },
+    {
+      "login": "cjwyett",
+      "name": "Cyrus Wyett",
+      "avatar_url": "https://avatars.githubusercontent.com/u/34195737?v=4",
+      "profile": "https://github.com/cjwyett",
+      "contributions": [
+        "content"
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+    {
+      "login": "cadolphs",
+      "name": "cadolphs",
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+        "code"
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+    {
+      "login": "hpwxf",
+      "name": "Pascal H.",
+      "avatar_url": "https://avatars.githubusercontent.com/u/26146722?v=4",
+      "profile": "https://www.haveneer.com",
+      "contributions": [
+        "content"
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+    {
+      "login": "chapeupreto",
+      "name": "Rod Elias",
+      "avatar_url": "https://avatars.githubusercontent.com/u/834048?v=4",
+      "profile": "https://twitter.com/chapeupreto",
+      "contributions": [
+        "content"
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+    },
+    {
+      "login": "blerchy",
+      "name": "Matt Lebl",
+      "avatar_url": "https://avatars.githubusercontent.com/u/2555355?v=4",
+      "profile": "https://github.com/blerchy",
+      "contributions": [
+        "code"
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+    },
+    {
+      "login": "flakolefluk",
+      "name": "Ignacio Le Fluk",
+      "avatar_url": "https://avatars.githubusercontent.com/u/11986564?v=4",
+      "profile": "http://flakolefluk.dev",
+      "contributions": [
+        "content"
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+    },
+    {
+      "login": "tlyu",
+      "name": "Taylor Yu",
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+        "code",
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+    {
+      "login": "Zerotask",
+      "name": "Patrick Hintermayer",
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+    {
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+    {
+      "login": "hongshaoyang",
+      "name": "Shao Yang Hong",
+      "avatar_url": "https://avatars.githubusercontent.com/u/19281800?v=4",
+      "profile": "https://github.com/hongshaoyang",
+      "contributions": [
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+    {
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+      "name": "Brandon Macer",
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+      "profile": "https://github.com/bmacer",
+      "contributions": [
+        "content"
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+    }
+  ],
+  "contributorsPerLine": 8,
+  "projectName": "rustlings",
+  "projectOwner": "rust-lang",
+  "repoType": "github",
+  "repoHost": "https://github.com",
+  "skipCi": true
+}
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,5 @@ target/
 *.pdb
 exercises/clippy/Cargo.toml
 exercises/clippy/Cargo.lock
+.idea
+.vscode
--- a/.gitpod.yml
+++ b/.gitpod.yml
@@ -0,0 +1,7 @@
+tasks:
+  - init: /workspace/rustlings/install.sh
+    command: /workspace/.cargo/bin/rustlings watch
+
+vscode:
+  extensions:
+    - rust-lang.rust@0.7.8:CvNqMTgDdt3UXt+6BCDTVg==
--- a/.replit
+++ b/.replit
@@ -0,0 +1,2 @@
+language = "rust"
+run = "[ -x ~/.cargo/bin/rustlings ] && ~/.cargo/bin/rustlings watch || ./install.sh"
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,157 @@
+<a name="4.4.0"></a>
+## 4.4.0 (2021-04-24)
+
+
+#### Bug Fixes
+
+*   Fix spelling error in main.rs ([91ee27f2](https://github.com/rust-lang/rustlings/commit/91ee27f22bd3797a9db57e5fd430801c170c5db8))
+*   typo in default out text ([644c49f1](https://github.com/rust-lang/rustlings/commit/644c49f1e04cbb24e95872b3a52b07d692ae3bc8))
+* **collections:**  Naming exercises for vectors and hashmap ([bef39b12](https://github.com/rust-lang/rustlings/commit/bef39b125961310b34b34871e480a82e82af4678))
+* **from_str:**
+  *  Correct typos ([5f7c89f8](https://github.com/rust-lang/rustlings/commit/5f7c89f85db1f33da01911eaa479c3a2d4721678))
+  *  test for error instead of unwrap/should_panic ([15e71535](https://github.com/rust-lang/rustlings/commit/15e71535f37cfaed36e22eb778728d186e2104ab))
+  *   use trait objects for from_str ([c3e7b831](https://github.com/rust-lang/rustlings/commit/c3e7b831786c9172ed8bd5d150f3c432f242fba9))
+* **functions3:**  improve function argument type (#687) ([a6509cc4](https://github.com/rust-lang/rustlings/commit/a6509cc4d545d8825f01ddf7ee37823b372154dd))
+* **hashmap2:**  Update incorrect assertion (#660) ([72aaa15e](https://github.com/rust-lang/rustlings/commit/72aaa15e6ab4b72b3422f1c6356396e20a2a2bb8))
+* **info:**  Fix typo (#635) ([cddc1e86](https://github.com/rust-lang/rustlings/commit/cddc1e86e7ec744ee644cc774a4887b1a0ded3e8))
+* **iterators2:**  Moved errors out of tests. ([baf4ba17](https://github.com/rust-lang/rustlings/commit/baf4ba175ba6eb92989e3dd54ecbec4bedc9a863), closes [#359](https://github.com/rust-lang/rustlings/issues/359))
+* **iterators3:**  Enabled iterators3.rs to run without commented out tests. ([c6712dfc](https://github.com/rust-lang/rustlings/commit/c6712dfccd1a093e590ad22bbc4f49edc417dac0))
+* **main:**  Let find_exercise work with borrows ([347f30bd](https://github.com/rust-lang/rustlings/commit/347f30bd867343c5ace1097e085a1f7e356553f7))
+* **move_semantics4:**
+  *  Remove redundant "instead" (#640) ([cc266d7d](https://github.com/rust-lang/rustlings/commit/cc266d7d80b91e79df3f61984f231b7f1587218e))
+  *  Small readbility improvement (#617) ([10965920](https://github.com/rust-lang/rustlings/commit/10965920fbdf8a1efc85bed869e55a1787006404))
+* **option2:**  Rename uninformative variables (#675) ([b4de6594](https://github.com/rust-lang/rustlings/commit/b4de6594380636817d13c2677ec6f472a964cf43))
+* **quiz3:**  Force an answer to Q2 (#672) ([0d894e6f](https://github.com/rust-lang/rustlings/commit/0d894e6ff739943901e1ae8c904582e5c2f843bd))
+* **structs:**  Add 5.3 to structs/README (#652) ([6bd791f2](https://github.com/rust-lang/rustlings/commit/6bd791f2f44aa7f0ad926df767f6b1fa8f12a9a9))
+* **structs2:**  correct grammar in hint (#663) ([ebdb66c7](https://github.com/rust-lang/rustlings/commit/ebdb66c7bfb6d687a14cc511a559a222e6fc5de4))
+* **structs3:**
+  * reword heading comment (#664) ([9f3e8c2d](https://github.com/rust-lang/rustlings/commit/9f3e8c2dde645e5264c2d2200e68842b5f47bfa3))
+  *   add check to prevent naive implementation of is_international ([05a753fe](https://github.com/rust-lang/rustlings/commit/05a753fe6333d36dbee5f68c21dec04eacdc75df))
+* **threads1:**  line number correction ([7857b0a6](https://github.com/rust-lang/rustlings/commit/7857b0a689b0847f48d8c14cbd1865e3b812d5ca))
+* **try_from_into:**  use trait objects ([2e93a588](https://github.com/rust-lang/rustlings/commit/2e93a588e0abe8badb7eafafb9e7d073c2be5df8))
+
+#### Features
+
+*   Replace clap with argh ([7928122f](https://github.com/rust-lang/rustlings/commit/7928122fcef9ca7834d988b1ec8ca0687478beeb))
+*   Replace emojis when NO_EMOJI env variable present ([8d62a996](https://github.com/rust-lang/rustlings/commit/8d62a9963708dbecd9312e8bcc4b47049c72d155))
+*   Added iterators5.rs exercise. ([b29ea17e](https://github.com/rust-lang/rustlings/commit/b29ea17ea94d1862114af2cf5ced0e09c197dc35))
+* **arc1:**  Add more details to description and hint (#710) ([81be4044](https://github.com/rust-lang/rustlings/commit/81be40448777fa338ebced3b0bfc1b32d6370313))
+* **cli:**  Improve the list command with options, and then some ([8bbe4ff1](https://github.com/rust-lang/rustlings/commit/8bbe4ff1385c5c169c90cd3ff9253f9a91daaf8e))
+* **list:**
+  *  updated progress percentage ([1c6f7e4b](https://github.com/rust-lang/rustlings/commit/1c6f7e4b7b9b3bd36f4da2bb2b69c549cc8bd913))
+  *  added progress info ([c0e3daac](https://github.com/rust-lang/rustlings/commit/c0e3daacaf6850811df5bc57fa43e0f249d5cfa4))
+
+
+
+<a name="4.3.0"></a>
+## 4.3.0 (2020-12-29)
+
+#### Features
+
+*   Rewrite default out text ([44d39112](https://github.com/rust-lang/rustlings/commit/44d39112ff122b29c9793fe52e605df1612c6490))
+*   match exercise order to book chapters (#541) ([033bf119](https://github.com/rust-lang/rustlings/commit/033bf1198fc8bfce1b570e49da7cde010aa552e3))
+*   Crab? (#586) ([fa9f522b](https://github.com/rust-lang/rustlings/commit/fa9f522b7f043d7ef73a39f003a9272dfe72c4f4))
+*   add "rustlings list" command ([838f9f30](https://github.com/rust-lang/rustlings/commit/838f9f30083d0b23fd67503dcf0fbeca498e6647))
+* **try_from_into:**  remove duplicate annotation ([04f1d079](https://github.com/rust-lang/rustlings/commit/04f1d079aa42a2f49af694bc92c67d731d31a53f))
+
+#### Bug Fixes
+
+*   update structs README ([bcf14cf6](https://github.com/rust-lang/rustlings/commit/bcf14cf677adb3a38a3ac3ca53f3c69f61153025))
+*   added missing exercises to info.toml ([90cfb6ff](https://github.com/rust-lang/rustlings/commit/90cfb6ff28377531bfc34acb70547bdb13374f6b))
+*   gives a bit more context to magic number ([30644c9a](https://github.com/rust-lang/rustlings/commit/30644c9a062b825c0ea89435dc59f0cad86b110e))
+* **functions2:**  Change signature to trigger precise error message: (#605) ([0ef95947](https://github.com/rust-lang/rustlings/commit/0ef95947cc30482e63a7045be6cc2fb6f6dcb4cc))
+* **structs1:**  Adjust wording (#573) ([9334783d](https://github.com/rust-lang/rustlings/commit/9334783da31d821cc59174fbe8320df95828926c))
+* **try_from_into:**
+  *  type error ([4f4cfcf3](https://github.com/rust-lang/rustlings/commit/4f4cfcf3c36c8718c7c170c9c3a6935e6ef0618c))
+  *  Update description (#584) ([96347df9](https://github.com/rust-lang/rustlings/commit/96347df9df294f01153b29d9ad4ba361f665c755))
+* **vec1:**  Have test compare every element in a and v ([9b6c6293](https://github.com/rust-lang/rustlings/commit/9b6c629397b24b944f484f5b2bbd8144266b5695))
+
+<a name="4.2.0"></a>
+## 4.2.0 (2020-11-07)
+
+#### Features
+
+*   Add HashMap exercises ([633c00cf](https://github.com/rust-lang/rustlings/commit/633c00cf8071e1e82959a3010452a32f34f29fc9))
+*   Add Vec exercises ([0c12fa31](https://github.com/rust-lang/rustlings/commit/0c12fa31c57c03c6287458a0a8aca7afd057baf6))
+* **primitive_types6:**  Add a test (#548) ([2b1fb2b7](https://github.com/rust-lang/rustlings/commit/2b1fb2b739bf9ad8d6b7b12af25fee173011bfc4))
+* **try_from_into:**  Add tests (#571) ([95ccd926](https://github.com/rust-lang/rustlings/commit/95ccd92616ae79ba287cce221101e0bbe4f68cdc))
+
+#### Bug Fixes
+
+*   log error output when inotify limit is exceeded ([d61b4e5a](https://github.com/rust-lang/rustlings/commit/d61b4e5a13b44d72d004082f523fa1b6b24c1aca))
+*   more unique temp_file ([5643ef05](https://github.com/rust-lang/rustlings/commit/5643ef05bc81e4a840e9456f4406a769abbe1392))
+* **installation:**  Update the MinRustVersion ([21bfb2d4](https://github.com/rust-lang/rustlings/commit/21bfb2d4777429c87d8d3b5fbf0ce66006dcd034))
+* **iterators2:**  Update description (#578) ([197d3a3d](https://github.com/rust-lang/rustlings/commit/197d3a3d8961b2465579218a6749b2b2cefa8ddd))
+* **primitive_types6:**
+  *  remove 'unused doc comment' warning ([472d8592](https://github.com/rust-lang/rustlings/commit/472d8592d65c8275332a20dfc269e7ac0d41bc88))
+  *  missing comma in test ([4fb230da](https://github.com/rust-lang/rustlings/commit/4fb230daf1251444fcf29e085cee222a91f8a37e))
+* **quiz3:**  Second test is for odd numbers, not even. (#553) ([18e0bfef](https://github.com/rust-lang/rustlings/commit/18e0bfef1de53071e353ba1ec5837002ff7290e6))
+
+<a name="4.1.0"></a>
+## 4.1.0 (2020-10-05)
+
+#### Bug Fixes
+
+*   Update rustlings version in Cargo.lock ([1cc40bc9](https://github.com/rust-lang/rustlings/commit/1cc40bc9ce95c23d56f6d91fa1c4deb646231fef))
+* **arc1:**  index mod should equal thread count ([b4062ef6](https://github.com/rust-lang/rustlings/commit/b4062ef6993e80dac107c4093ea85166ad3ee0fa))
+* **enums3:**  Update Message::ChangeColor to take a tuple. (#457) ([4b6540c7](https://github.com/rust-lang/rustlings/commit/4b6540c71adabad647de8a09e57295e7c7c7d794))
+* **exercises:**  adding question mark to quiz2 ([101072ab](https://github.com/rust-lang/rustlings/commit/101072ab9f8c80b40b8b88cb06cbe38aca2481c5))
+* **generics3:**  clarify grade change ([47f7672c](https://github.com/rust-lang/rustlings/commit/47f7672c0307732056e7426e81d351f0dd7e22e5))
+* **structs3:**  Small adjustment of variable name ([114b54cb](https://github.com/rust-lang/rustlings/commit/114b54cbdb977234b39e5f180d937c14c78bb8b2))
+* **using_as:**  Add test so that proper type is returned. (#512) ([3286c5ec](https://github.com/rust-lang/rustlings/commit/3286c5ec19ea5fb7ded81d047da5f8594108a490))
+
+#### Features
+
+*   Added iterators1.rs exercise ([9642f5a3](https://github.com/rust-lang/rustlings/commit/9642f5a3f686270a4f8f6ba969919ddbbc4f7fdd))
+*   Add ability to run rustlings on repl.it (#471) ([8f7b5bd0](https://github.com/rust-lang/rustlings/commit/8f7b5bd00eb83542b959830ef55192d2d76db90a))
+*   Add gitpod support (#473) ([4821a8be](https://github.com/rust-lang/rustlings/commit/4821a8be94af4f669042a06ab917934cfacd032f))
+*   Remind the user of the hint option (#425) ([816b1f5e](https://github.com/rust-lang/rustlings/commit/816b1f5e85d6cc6e72673813a85d0ada2a8f84af))
+*   Remind the user of the hint option (#425) ([9f61db5d](https://github.com/rust-lang/rustlings/commit/9f61db5dbe38538cf06571fcdd5f806e7901e83a))
+* **cli:**  Added 'cls' command to 'watch' mode (#474) ([4f2468e1](https://github.com/rust-lang/rustlings/commit/4f2468e14f574a93a2e9b688367b5752ed96ae7b))
+* **try_from_into:**  Add insufficient length test (#469) ([523d18b8](https://github.com/rust-lang/rustlings/commit/523d18b873a319f7c09262f44bd40e2fab1830e5))
+
+<a name="4.0.0"></a>
+## 4.0.0 (2020-07-08)
+
+#### Breaking Changes
+
+*   Add a --nocapture option to display test harnesses' outputs ([8ad5f9bf](https://github.com/rust-lang/rustlings/commit/8ad5f9bf531a4848b1104b7b389a20171624c82f))
+*   Rename test to quiz, fixes #244 ([010a0456](https://github.com/rust-lang/rustlings/commit/010a04569282149cea7f7a76fc4d7f4c9f0f08dd))
+
+#### Features
+
+*   Add traits README ([173bb141](https://github.com/rust-lang/rustlings/commit/173bb14140c5530cbdb59e53ace3991a99d804af))
+*   Add box1.rs exercise ([7479a473](https://github.com/rust-lang/rustlings/commit/7479a4737bdcac347322ad0883ca528c8675e720))
+*   Rewrite try_from_into (#393) ([763aa6e3](https://github.com/rust-lang/rustlings/commit/763aa6e378a586caae2d8d63755a85eeba227933))
+*   Add if2 exercise ([1da84b5f](https://github.com/rust-lang/rustlings/commit/1da84b5f7c489f65bd683c244f13c7d1ee812df0))
+*   Added exercise structs3.rs ([b66e2e09](https://github.com/rust-lang/rustlings/commit/b66e2e09622243e086a0f1258dd27e1a2d61c891))
+*   Add exercise variables6 covering const (#352) ([5999acd2](https://github.com/rust-lang/rustlings/commit/5999acd24a4f203292be36e0fd18d385887ec481))
+
+#### Bug Fixes
+
+*   Change then to than ([ddd98ad7](https://github.com/rust-lang/rustlings/commit/ddd98ad75d3668fbb10eff74374148aa5ed2344d))
+*   rename quiz1 to tests1 in info (#420) ([0dd1c6ca](https://github.com/rust-lang/rustlings/commit/0dd1c6ca6b389789e0972aa955fe17aa15c95f29))
+*   fix quiz naming inconsistency (#421) ([5563adbb](https://github.com/rust-lang/rustlings/commit/5563adbb890587fc48fbbc9c4028642687f1e85b))
+*   confine the user further in variable exercises ([06ef4cc6](https://github.com/rust-lang/rustlings/commit/06ef4cc654e75d22a526812919ee49b8956280bf))
+*   update iterator and macro text for typos and clarity ([95900828](https://github.com/rust-lang/rustlings/commit/959008284834bece0196a01e17ac69a7e3590116))
+*   update generics2       closes #362 ([964c974a](https://github.com/rust-lang/rustlings/commit/964c974a0274199d755073b917c2bc5da0c9b4f1))
+*   confusing comment in conversions/try_from_into.rs ([c9e4f2cf](https://github.com/rust-lang/rustlings/commit/c9e4f2cfb4c48d0b7451263cfb43b9426438122d))
+* **arc1:**  Passively introduce attributes (#429) ([113cdae2](https://github.com/rust-lang/rustlings/commit/113cdae2d4e4c55905e8056ad326ede7fd7de356))
+* **box1:**  fix comment typo (#426) ([bb2ca251](https://github.com/rust-lang/rustlings/commit/bb2ca251106b27a7272d9a30872904dd1376654c))
+* **errorsn:**  Try harder to confine the user. (#388) ([2b20c8a0](https://github.com/rust-lang/rustlings/commit/2b20c8a0f5774d07c58d110d75879f33fc6273b5))
+* **from_into.rs:**  typo ([a901499e](https://github.com/rust-lang/rustlings/commit/a901499ededd3ce1995164700514fe4e9a0373ea))
+* **generics2:**  Guide students to the answer (#430) ([e6bd8021](https://github.com/rust-lang/rustlings/commit/e6bd8021d9a7dd06feebc30c9d5f953901d7b419))
+* **installation:**
+  *  Provide a backup git reference when tag can't be curl ([9e4fb100](https://github.com/rust-lang/rustlings/commit/9e4fb1009f1c9e3433915c03e22c2af422e5c5fe))
+  *  Check if python is available while checking for git,rustc and cargo ([9cfb617d](https://github.com/rust-lang/rustlings/commit/9cfb617d5b0451b4b51644a1298965390cda9884))
+* **option1:**
+  *  Don't add only zeros to the numbers array ([cce6a442](https://github.com/rust-lang/rustlings/commit/cce6a4427718724a9096800754cd3abeca6a1580))
+  *  Add cast to usize, as it is confusing in the context of an exercise about Option ([f6cffc7e](https://github.com/rust-lang/rustlings/commit/f6cffc7e487b42f15a6f958e49704c93a8d4465b))
+* **option2:**  Add TODO to comments (#400) ([10967bce](https://github.com/rust-lang/rustlings/commit/10967bce57682812dc0891a9f9757da1a9d87404))
+* **options1:**  Add hint about Array Initialization (#389) ([9f75554f](https://github.com/rust-lang/rustlings/commit/9f75554f2a30295996f03f0160b98c0458305502))
+* **test2:**  name of type String and &str (#394) ([d6c0a688](https://github.com/rust-lang/rustlings/commit/d6c0a688e6a96f93ad60d540d4b326f342fc0d45))
+* **variables6:**  minor typo (#419) ([524e17df](https://github.com/rust-lang/rustlings/commit/524e17df10db95f7b90a0f75cc8997182a8a4094))
+
 <a name="3.0.0"></a>
 ## 3.0.0 (2020-04-11)

@@ -41,14 +195,14 @@
 *   Update deps to version compatable with aarch64-pc-windows (#263) ([19a93428](https://github.com/rust-lang/rustlings/commit/19a93428b3c73d994292671f829bdc8e5b7b3401))
 * **docs:**
  * Added a necessary step to Windows installation process (#242) ([3906efcd](https://github.com/rust-lang/rustlings/commit/3906efcd52a004047b460ed548037093de3f523f))
-  * Fixed mangled sentence from book; edited for clarity (#266) ([ade52ff](https://github.com/rust-lang/rustlings/commit/ade52ffb739987287ddd5705944c8777705faed9)) 
+  * Fixed mangled sentence from book; edited for clarity (#266) ([ade52ff](https://github.com/rust-lang/rustlings/commit/ade52ffb739987287ddd5705944c8777705faed9))
  * Updated iterators readme to account for iterators4 exercise (#273) ([bec8e3a](https://github.com/rust-lang/rustlings/commit/bec8e3a644cbd88db1c73ea5f1d8a364f4a34016))
 * **installation:**  make fatal errors more obvious (#272) ([17d0951e](https://github.com/rust-lang/rustlings/commit/17d0951e66fda8e11b204d5c4c41a0d5e22e78f7))
 * **iterators2:**
  *  Remove reference to missing iterators2.rs (#245) ([419f7797](https://github.com/rust-lang/rustlings/commit/419f7797f294e4ce6a2b883199731b5bde77d262))
 * **as_ref_mut:** Enable a test and improve per clippy's suggestion (#256) ([dfdf809](https://github.com/rust-lang/rustlings/commit/dfdf8093ebbd4145864995627b812780de52f902))
 * **tests1:**
-  * Change test command ([fe10e06c](https://github.com/rust-lang/rustlings/commit/fe10e06c3733ddb4a21e90d09bf79bfe618e97ce) 
+  * Change test command ([fe10e06c](https://github.com/rust-lang/rustlings/commit/fe10e06c3733ddb4a21e90d09bf79bfe618e97ce)
  * Correct test command in tests1.rs comment (#263) ([39fa7ae](https://github.com/rust-lang/rustlings/commit/39fa7ae8b70ad468da49b06f11b2383135a63bcf))

 #### Features
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -26,12 +26,12 @@ isn't really that complicated since the bulk of the work is done by `rustc`.
 <a name="addex"></a>
 ### Adding an exercise

-First step is to add the exercise! Call it `exercises/yourTopic/yourTopicN.rs`, make sure to
+The first step is to add the exercise! Name the file `exercises/yourTopic/yourTopicN.rs`, make sure to
 put in some helpful links, and link to sections of the book in `exercises/yourTopic/README.md`.

-Next you want to make sure it runs when using `rustlings`. All exercises are stored in `info.toml`, under the `exercises` array. They're ordered by the order they're ran when using `rustlings verify`.
+Next make sure it runs with `rustlings`. The exercise metadata is stored in `info.toml`, under the `exercises` array. The order of the `exercises` array determines the order the exercises are run by `rustlings verify`.

-You want to make sure where in the file you add your exercise. If you're not sure, add it at the bottom and ask in your pull request. To add an exercise, edit the file like this:
+Add the metadata for your exercise in the correct order in the `exercises` array. If you are unsure of the correct ordering, add it at the bottom and ask in your pull request. The exercise metadata should contain the following:
 ```diff
  ...
 + [[exercises]]
--- a/Cargo.lock
+++ b/Cargo.lock
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,11 +1,11 @@
 [package]
 name = "rustlings"
-version = "3.0.0"
+version = "4.4.0"
 authors = ["Marisa <mokou@posteo.de>", "Carol (Nichols || Goulding) <carol.nichols@gmail.com>"]
 edition = "2018"

 [dependencies]
-clap = "2.32.0"
+argh = "0.1.4"
 indicatif = "0.10.3"
 console = "0.7.7"
 notify = "4.0.15"
--- a/README.md
+++ b/README.md
@@ -1,12 +1,14 @@
-![crab pet](https://i.imgur.com/LbZJgmm.gif)
+<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
+[![All Contributors](https://img.shields.io/badge/all_contributors-90-orange.svg?style=flat-square)](#contributors-)
+<!-- ALL-CONTRIBUTORS-BADGE:END -->

-# rustlings 🦀❤️ [![Build status](https://badge.buildkite.com/7af93d81dc522c67a1ec8e33ff5705861b1cb36360b774807f.svg)](https://buildkite.com/mokou/rustlings)
+# rustlings 🦀❤️

 Greetings and welcome to `rustlings`. This project contains small exercises to get you used to reading and writing Rust code. This includes reading and responding to compiler messages!

 _...looking for the old, web-based version of Rustlings? Try [here](https://github.com/rust-lang/rustlings/tree/rustlings-1)_

-Alternatively, for a first-time Rust learner, there's several other resources:
+Alternatively, for a first-time Rust learner, there are several other resources:

 - [The Book](https://doc.rust-lang.org/book/index.html) - The most comprehensive resource for learning Rust, but a bit theoretical sometimes. You will be using this along with Rustlings!
 - [Rust By Example](https://doc.rust-lang.org/rust-by-example/index.html) - Learn Rust by solving little exercises! It's almost like `rustlings`, but online
@@ -15,8 +17,6 @@ Alternatively, for a first-time Rust learner, there's several other resources:

 _Note: If you're on MacOS, make sure you've installed Xcode and its developer tools by typing `xcode-select --install`._

-_Note: If you have Xcode 10+ installed, you also need to install the package file found at `/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg`._
-
 You will need to have Rust installed. You can get it by visiting https://rustup.rs. This'll also install Cargo, Rust's package/project manager.

 ## MacOS/Linux
@@ -24,16 +24,16 @@ You will need to have Rust installed. You can get it by visiting https://rustup.
 Just run:

 ```bash
-curl -L https://git.io/rustlings | bash
+curl -L https://git.io/install-rustlings | bash
 # Or if you want it to be installed to a different path:
-curl -L https://git.io/rustlings | bash -s mypath/
+curl -L https://git.io/install-rustlings | bash -s mypath/
 ```

 This will install Rustlings and give you access to the `rustlings` command. Run it to get started!

 ## Windows

-First, set `ExecutionPolicy` to `RemoteSigned`:
+In PowerShell, set `ExecutionPolicy` to `RemoteSigned`:

 ```ps
 Set-ExecutionPolicy RemoteSigned
@@ -42,11 +42,19 @@ Set-ExecutionPolicy RemoteSigned
 Then, you can run:

 ```ps
-Invoke-WebRequest https://git.io/rustlings-win | Select-Object -ExpandProperty Content | Out-File $env:TMP/install_rustlings.ps1; Unblock-File $env:TMP/install_rustlings.ps1; Invoke-Expression $env:TMP/install_rustlings.ps1
+Start-BitsTransfer -Source https://git.io/JTL5v -Destination $env:TMP/install_rustlings.ps1; Unblock-File $env:TMP/install_rustlings.ps1; Invoke-Expression $env:TMP/install_rustlings.ps1
 ```

 To install Rustlings. Same as on MacOS/Linux, you will have access to the `rustlings` command after it.

+When you get a permission denied message then you have to exclude the directory where you placed the rustlings in your virus-scanner
+
+## Browser:
+
+[Run on Repl.it](https://repl.it/github/rust-lang/rustlings)
+
+[Open in Gitpod](https://gitpod.io/#https://github.com/rust-lang/rustlings)
+
 ## Manually

 Basically: Clone the repository, checkout to the latest tag, run `cargo install`.
@@ -54,7 +62,7 @@ Basically: Clone the repository, checkout to the latest tag, run `cargo install`
 ```bash
 git clone https://github.com/rust-lang/rustlings
 cd rustlings
-git checkout tags/3.0.0 # or whatever the latest version is (find out at https://github.com/rust-lang/rustlings/releases/latest)
+git checkout tags/4.4.0 # or whatever the latest version is (find out at https://github.com/rust-lang/rustlings/releases/latest)
 cargo install --force --path .
 ```

@@ -69,7 +77,7 @@ Then, same as above, run `rustlings` to get started.

 The exercises are sorted by topic and can be found in the subdirectory `rustlings/exercises/<topic>`. For every topic there is an additional README file with some resources to get you started on the topic. We really recommend that you have a look at them before you start.

-The task is simple. Most exercises contain an error that keep it from compiling, and it's up to you to fix it! Some exercises are also run as tests, but rustlings handles them all the same. To run the exercises in the recommended order, execute:
+The task is simple. Most exercises contain an error that keeps them from compiling, and it's up to you to fix it! Some exercises are also run as tests, but rustlings handles them all the same. To run the exercises in the recommended order, execute:

 ```bash
 rustlings watch
@@ -96,9 +104,36 @@ exercise:
 rustlings hint myExercise1
 ```

+To check your progress, you can run the following command:
+```bash
+rustlings list
+```
+
 ## Testing yourself

-After every couple of sections, there will be a test that'll test your knowledge on a bunch of sections at once. These tests are found in `exercises/testN.rs`.
+After every couple of sections, there will be a quiz that'll test your knowledge on a bunch of sections at once. These quizzes are found in `exercises/quizN.rs`.
+
+## Continuing On
+
+Once you've completed Rustlings, put your new knowledge to good use! Continue practicing your Rust skills by building your own projects, contributing to Rustlings, or finding other open-source projects to contribute to.
+
+## Uninstalling Rustlings
+
+If you want to remove Rustlings from your system, there's two steps. First, you'll need to remove the exercises folder that the install script created
+for you:
+
+``` bash
+rm -rf rustlings # or your custom folder name, if you chose and or renamed it
+```
+
+Second, since Rustlings got installed via `cargo install`, it's only reasonable to assume that you can also remove it using Cargo, and
+exactly that is the case. Run `cargo uninstall` to remove the `rustlings` binary:
+
+``` bash
+cargo uninstall rustlings
+```
+
+Now you should be done!

 ## Completion

@@ -122,7 +157,133 @@ If you are interested in improving or adding new ones, please feel free to contr

 See [CONTRIBUTING.md](./CONTRIBUTING.md).

-## Credits
+## Contributors ✨

-`rustlings` was originally written by [Carol](https://github.com/carols10cents)!
+Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/docs/en/emoji-key)):

+<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<table>
+  <tr>
+    <td align="center"><a href="http://carol-nichols.com"><img src="https://avatars2.githubusercontent.com/u/193874?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Carol (Nichols &#124;&#124; Goulding)</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=carols10cents" title="Code">💻</a> <a href="#content-carols10cents" title="Content">🖋</a></td>
+    <td align="center"><a href="https://twitter.com/QuietMisdreavus"><img src="https://avatars2.githubusercontent.com/u/5217170?v=4?s=100" width="100px;" alt=""/><br /><sub><b>QuietMisdreavus</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=QuietMisdreavus" title="Code">💻</a> <a href="#content-QuietMisdreavus" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/robertlugg"><img src="https://avatars0.githubusercontent.com/u/6054540?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Robert M Lugg</b></sub></a><br /><a href="#content-robertlugg" title="Content">🖋</a></td>
+    <td align="center"><a href="https://hynek.me/about/"><img src="https://avatars3.githubusercontent.com/u/41240?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Hynek Schlawack</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=hynek" title="Code">💻</a></td>
+    <td align="center"><a href="https://spacekookie.de"><img src="https://avatars0.githubusercontent.com/u/7669898?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Katharina Fey</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=spacekookie" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/lukabavdaz"><img src="https://avatars0.githubusercontent.com/u/9624558?v=4?s=100" width="100px;" alt=""/><br /><sub><b>lukabavdaz</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=lukabavdaz" title="Code">💻</a> <a href="#content-lukabavdaz" title="Content">🖋</a></td>
+    <td align="center"><a href="http://vestera.as"><img src="https://avatars2.githubusercontent.com/u/4187449?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Erik Vesteraas</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=evestera" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/Delet0r"><img src="https://avatars1.githubusercontent.com/u/23195618?v=4?s=100" width="100px;" alt=""/><br /><sub><b>delet0r</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Delet0r" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="http://phinary.ca"><img src="https://avatars1.githubusercontent.com/u/10522375?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shaun Bennett</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=shaunbennett" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/abagshaw"><img src="https://avatars2.githubusercontent.com/u/8594541?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Andrew Bagshaw</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=abagshaw" title="Code">💻</a></td>
+    <td align="center"><a href="https://ai6ua.net/"><img src="https://avatars2.githubusercontent.com/u/175578?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Kyle Isom</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=kisom" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/ColinPitrat"><img src="https://avatars3.githubusercontent.com/u/1541863?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Colin Pitrat</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ColinPitrat" title="Code">💻</a></td>
+    <td align="center"><a href="https://zacanger.com"><img src="https://avatars3.githubusercontent.com/u/12520493?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Zac Anger</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=zacanger" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/mgeier"><img src="https://avatars1.githubusercontent.com/u/705404?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matthias Geier</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=mgeier" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/cjpearce"><img src="https://avatars1.githubusercontent.com/u/3453268?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Chris Pearce</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=cjpearce" title="Code">💻</a></td>
+    <td align="center"><a href="https://yvan-sraka.github.io"><img src="https://avatars2.githubusercontent.com/u/705213?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Yvan Sraka</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=yvan-sraka" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/dendi239"><img src="https://avatars3.githubusercontent.com/u/16478650?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Denys Smirnov</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=dendi239" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/eddyp"><img src="https://avatars2.githubusercontent.com/u/123772?v=4?s=100" width="100px;" alt=""/><br /><sub><b>eddyp</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=eddyp" title="Code">💻</a></td>
+    <td align="center"><a href="http://about.me/BrianKung"><img src="https://avatars1.githubusercontent.com/u/2836167?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Brian Kung</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=briankung" title="Code">💻</a> <a href="#content-briankung" title="Content">🖋</a></td>
+    <td align="center"><a href="https://rcousineau.gitlab.io"><img src="https://avatars3.githubusercontent.com/u/281039?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Russell</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=miller-time" title="Code">💻</a></td>
+    <td align="center"><a href="http://danwilhelm.com"><img src="https://avatars3.githubusercontent.com/u/6137185?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dan Wilhelm</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=danwilhelm" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/Jesse-Cameron"><img src="https://avatars3.githubusercontent.com/u/3723654?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jesse</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Jesse-Cameron" title="Code">💻</a> <a href="#content-Jesse-Cameron" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/MrFroop"><img src="https://avatars3.githubusercontent.com/u/196700?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fredrik Jambrén</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=MrFroop" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/petemcfarlane"><img src="https://avatars3.githubusercontent.com/u/3472717?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pete McFarlane</b></sub></a><br /><a href="#content-petemcfarlane" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/nkanderson"><img src="https://avatars0.githubusercontent.com/u/4128825?v=4?s=100" width="100px;" alt=""/><br /><sub><b>nkanderson</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=nkanderson" title="Code">💻</a> <a href="#content-nkanderson" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/ajaxm"><img src="https://avatars0.githubusercontent.com/u/13360138?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ajax M</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ajaxm" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://dylnuge.com"><img src="https://avatars2.githubusercontent.com/u/118624?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dylan Nugent</b></sub></a><br /><a href="#content-Dylnuge" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/vyaslav"><img src="https://avatars0.githubusercontent.com/u/1385427?v=4?s=100" width="100px;" alt=""/><br /><sub><b>vyaslav</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=vyaslav" title="Code">💻</a> <a href="#content-vyaslav" title="Content">🖋</a></td>
+    <td align="center"><a href="https://join.sfxd.org"><img src="https://avatars1.githubusercontent.com/u/17297466?v=4?s=100" width="100px;" alt=""/><br /><sub><b>George</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=gdoenlen" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/nyxtom"><img src="https://avatars2.githubusercontent.com/u/222763?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Thomas Holloway</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=nyxtom" title="Code">💻</a> <a href="#content-nyxtom" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/workingjubilee"><img src="https://avatars1.githubusercontent.com/u/46493976?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jubilee</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=workingjubilee" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/WofWca"><img src="https://avatars1.githubusercontent.com/u/39462442?v=4?s=100" width="100px;" alt=""/><br /><sub><b>WofWca</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=WofWca" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/jrvidal"><img src="https://avatars0.githubusercontent.com/u/1636604?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Roberto Vidal</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=jrvidal" title="Code">💻</a> <a href="https://github.com/rust-lang/rustlings/commits?author=jrvidal" title="Documentation">📖</a> <a href="#ideas-jrvidal" title="Ideas, Planning, & Feedback">🤔</a> <a href="#maintenance-jrvidal" title="Maintenance">🚧</a></td>
+    <td align="center"><a href="https://github.com/jensim"><img src="https://avatars0.githubusercontent.com/u/3663856?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jens</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=jensim" title="Documentation">📖</a></td>
+    <td align="center"><a href="http://rahatah.me/d"><img src="https://avatars3.githubusercontent.com/u/3174006?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rahat Ahmed</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=rahatarmanahmed" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/AbdouSeck"><img src="https://avatars2.githubusercontent.com/u/6490055?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Abdou Seck</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=AbdouSeck" title="Code">💻</a> <a href="#content-AbdouSeck" title="Content">🖋</a> <a href="https://github.com/rust-lang/rustlings/pulls?q=is%3Apr+reviewed-by%3AAbdouSeck" title="Reviewed Pull Requests">👀</a></td>
+    <td align="center"><a href="https://codehearts.com"><img src="https://avatars0.githubusercontent.com/u/2885412?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Katie</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=codehearts" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/Socratides"><img src="https://avatars3.githubusercontent.com/u/27732983?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Socrates</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Socratides" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/gnodarse"><img src="https://avatars3.githubusercontent.com/u/46761795?v=4?s=100" width="100px;" alt=""/><br /><sub><b>gnodarse</b></sub></a><br /><a href="#content-gnodarse" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/harrisonmetz"><img src="https://avatars1.githubusercontent.com/u/7883408?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Harrison Metzger</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=harrisonmetz" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/TorbenJ"><img src="https://avatars2.githubusercontent.com/u/9077102?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Torben Jonas</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=TorbenJ" title="Code">💻</a> <a href="#content-TorbenJ" title="Content">🖋</a></td>
+    <td align="center"><a href="http://paulbissex.com/"><img src="https://avatars0.githubusercontent.com/u/641?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Paul Bissex</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=pbx" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/sjmann"><img src="https://avatars0.githubusercontent.com/u/6589896?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Steven Mann</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=sjmann" title="Code">💻</a> <a href="#content-sjmann" title="Content">🖋</a></td>
+    <td align="center"><a href="https://smmdb.net/"><img src="https://avatars2.githubusercontent.com/u/5855071?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mario Reder</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Tarnadas" title="Code">💻</a> <a href="#content-Tarnadas" title="Content">🖋</a></td>
+    <td align="center"><a href="https://keybase.io/skim"><img src="https://avatars0.githubusercontent.com/u/47347?v=4?s=100" width="100px;" alt=""/><br /><sub><b>skim</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=sl4m" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/sanjaykdragon"><img src="https://avatars1.githubusercontent.com/u/10261698?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sanjay K</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=sanjaykdragon" title="Code">💻</a> <a href="#content-sanjaykdragon" title="Content">🖋</a></td>
+    <td align="center"><a href="http://www.rohanjain.in"><img src="https://avatars1.githubusercontent.com/u/343499?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rohan Jain</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=crodjer" title="Code">💻</a></td>
+    <td align="center"><a href="https://www.saidaspen.se"><img src="https://avatars1.githubusercontent.com/u/7727687?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Said Aspen</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=saidaspen" title="Code">💻</a> <a href="#content-saidaspen" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/uce"><img src="https://avatars3.githubusercontent.com/u/1756620?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ufuk Celebi</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=uce" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/lebedevsergey"><img src="https://avatars2.githubusercontent.com/u/7325764?v=4?s=100" width="100px;" alt=""/><br /><sub><b>lebedevsergey</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=lebedevsergey" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://github.com/avrong"><img src="https://avatars2.githubusercontent.com/u/6342851?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Aleksei Trifonov</b></sub></a><br /><a href="#content-avrong" title="Content">🖋</a></td>
+    <td align="center"><a href="https://drn.ie"><img src="https://avatars2.githubusercontent.com/u/411136?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Darren Meehan</b></sub></a><br /><a href="#content-Darrenmeehan" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/jihchi"><img src="https://avatars1.githubusercontent.com/u/87983?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jihchi Lee</b></sub></a><br /><a href="#content-jihchi" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/bertonha"><img src="https://avatars3.githubusercontent.com/u/1225902?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christofer Bertonha</b></sub></a><br /><a href="#content-bertonha" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/apatniv"><img src="https://avatars2.githubusercontent.com/u/22565917?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Vivek Bharath Akupatni</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=apatniv" title="Code">💻</a> <a href="https://github.com/rust-lang/rustlings/commits?author=apatniv" title="Tests">⚠️</a></td>
+    <td align="center"><a href="https://github.com/DiD92"><img src="https://avatars3.githubusercontent.com/u/6002416?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dídac Sementé Fernández</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=DiD92" title="Code">💻</a> <a href="#content-DiD92" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/wrobstory"><img src="https://avatars3.githubusercontent.com/u/2601457?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rob Story</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=wrobstory" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/siobhanjacobson"><img src="https://avatars2.githubusercontent.com/u/28983835?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Siobhan Jacobson</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=siobhanjacobson" title="Code">💻</a></td>
+    <td align="center"><a href="https://www.linkedin.com/in/evancarroll/"><img src="https://avatars2.githubusercontent.com/u/19922?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Evan Carroll</b></sub></a><br /><a href="#content-EvanCarroll" title="Content">🖋</a></td>
+    <td align="center"><a href="http://www.jawaadmahmood.com"><img src="https://avatars3.githubusercontent.com/u/95606?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jawaad Mahmood</b></sub></a><br /><a href="#content-jmahmood" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/GaurangTandon"><img src="https://avatars1.githubusercontent.com/u/6308683?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Gaurang Tandon</b></sub></a><br /><a href="#content-GaurangTandon" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/dev-cyprium"><img src="https://avatars1.githubusercontent.com/u/6002628?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Stefan Kupresak</b></sub></a><br /><a href="#content-dev-cyprium" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/greg-el"><img src="https://avatars3.githubusercontent.com/u/45019882?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Greg Leonard</b></sub></a><br /><a href="#content-greg-el" title="Content">🖋</a></td>
+    <td align="center"><a href="https://ryanpcmcquen.org"><img src="https://avatars3.githubusercontent.com/u/772937?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ryan McQuen</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ryanpcmcquen" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/AnnikaCodes"><img src="https://avatars3.githubusercontent.com/u/56906084?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Annika</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/pulls?q=is%3Apr+reviewed-by%3AAnnikaCodes" title="Reviewed Pull Requests">👀</a></td>
+    <td align="center"><a href="https://darnuria.eu"><img src="https://avatars1.githubusercontent.com/u/2827553?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Axel Viala</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=darnuria" title="Code">💻</a></td>
+    <td align="center"><a href="https://sazid.github.io"><img src="https://avatars1.githubusercontent.com/u/2370167?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mohammed Sazid Al Rashid</b></sub></a><br /><a href="#content-sazid" title="Content">🖋</a> <a href="https://github.com/rust-lang/rustlings/commits?author=sazid" title="Code">💻</a></td>
+    <td align="center"><a href="https://codingthemsoftly.com"><img src="https://avatars1.githubusercontent.com/u/17479099?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Caleb Webber</b></sub></a><br /><a href="#maintenance-seeplusplus" title="Maintenance">🚧</a></td>
+    <td align="center"><a href="https://github.com/pcn"><img src="https://avatars2.githubusercontent.com/u/1056756?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Peter N</b></sub></a><br /><a href="#maintenance-pcn" title="Maintenance">🚧</a></td>
+    <td align="center"><a href="https://github.com/seancad"><img src="https://avatars1.githubusercontent.com/u/47405611?v=4?s=100" width="100px;" alt=""/><br /><sub><b>seancad</b></sub></a><br /><a href="#maintenance-seancad" title="Maintenance">🚧</a></td>
+    <td align="center"><a href="http://willhayworth.com"><img src="https://avatars3.githubusercontent.com/u/181174?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Will Hayworth</b></sub></a><br /><a href="#content-wsh" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/chrizel"><img src="https://avatars3.githubusercontent.com/u/20802?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Christian Zeller</b></sub></a><br /><a href="#content-chrizel" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/jfchevrette"><img src="https://avatars.githubusercontent.com/u/3001?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Jean-Francois Chevrette</b></sub></a><br /><a href="#content-jfchevrette" title="Content">🖋</a> <a href="https://github.com/rust-lang/rustlings/commits?author=jfchevrette" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/jbaber"><img src="https://avatars.githubusercontent.com/u/1908117?v=4?s=100" width="100px;" alt=""/><br /><sub><b>John Baber-Lucero</b></sub></a><br /><a href="#content-jbaber" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/tal-zvon"><img src="https://avatars.githubusercontent.com/u/3195851?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Tal</b></sub></a><br /><a href="#content-tal-zvon" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/apogeeoak"><img src="https://avatars.githubusercontent.com/u/59737221?v=4?s=100" width="100px;" alt=""/><br /><sub><b>apogeeoak</b></sub></a><br /><a href="#content-apogeeoak" title="Content">🖋</a> <a href="https://github.com/rust-lang/rustlings/commits?author=apogeeoak" title="Code">💻</a></td>
+    <td align="center"><a href="http://www.garfieldtech.com/"><img src="https://avatars.githubusercontent.com/u/254863?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Larry Garfield</b></sub></a><br /><a href="#content-Crell" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/circumspect"><img src="https://avatars.githubusercontent.com/u/40770208?v=4?s=100" width="100px;" alt=""/><br /><sub><b>circumspect</b></sub></a><br /><a href="#content-circumspect" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/cjwyett"><img src="https://avatars.githubusercontent.com/u/34195737?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Cyrus Wyett</b></sub></a><br /><a href="#content-cjwyett" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/cadolphs"><img src="https://avatars.githubusercontent.com/u/13894820?v=4?s=100" width="100px;" alt=""/><br /><sub><b>cadolphs</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=cadolphs" title="Code">💻</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://www.haveneer.com"><img src="https://avatars.githubusercontent.com/u/26146722?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pascal H.</b></sub></a><br /><a href="#content-hpwxf" title="Content">🖋</a></td>
+    <td align="center"><a href="https://twitter.com/chapeupreto"><img src="https://avatars.githubusercontent.com/u/834048?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rod Elias</b></sub></a><br /><a href="#content-chapeupreto" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/blerchy"><img src="https://avatars.githubusercontent.com/u/2555355?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Matt Lebl</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=blerchy" title="Code">💻</a></td>
+    <td align="center"><a href="http://flakolefluk.dev"><img src="https://avatars.githubusercontent.com/u/11986564?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ignacio Le Fluk</b></sub></a><br /><a href="#content-flakolefluk" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/tlyu"><img src="https://avatars.githubusercontent.com/u/431873?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Taylor Yu</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=tlyu" title="Code">💻</a> <a href="#content-tlyu" title="Content">🖋</a></td>
+    <td align="center"><a href="https://zerotask.github.io"><img src="https://avatars.githubusercontent.com/u/20150243?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Patrick Hintermayer</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=Zerotask" title="Code">💻</a></td>
+    <td align="center"><a href="https://petkopavlovski.com/"><img src="https://avatars.githubusercontent.com/u/32264020?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Pete Pavlovski</b></sub></a><br /><a href="#content-arthas168" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/k12ish"><img src="https://avatars.githubusercontent.com/u/45272873?v=4?s=100" width="100px;" alt=""/><br /><sub><b>k12ish</b></sub></a><br /><a href="#content-k12ish" title="Content">🖋</a></td>
+  </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/hongshaoyang"><img src="https://avatars.githubusercontent.com/u/19281800?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Shao Yang Hong</b></sub></a><br /><a href="#content-hongshaoyang" title="Content">🖋</a></td>
+    <td align="center"><a href="https://github.com/bmacer"><img src="https://avatars.githubusercontent.com/u/13931806?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Brandon Macer</b></sub></a><br /><a href="#content-bmacer" title="Content">🖋</a></td>
+  </tr>
+</table>
+
+<!-- markdownlint-restore -->
+<!-- prettier-ignore-end -->
+
+<!-- ALL-CONTRIBUTORS-LIST:END -->
+
+This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
--- a/buildkite.yml
+++ b/buildkite.yml
@@ -1,5 +0,0 @@
-steps:
-  - label: "Test with stable"
-    command: rustup run stable cargo test
-  - label: "Test with beta"
-    command: rustup run beta cargo test
--- a/default_out.txt
+++ b/default_out.txt
@@ -1,19 +1,25 @@
 Thanks for installing Rustlings!

-Is this your first time?
+Is this your first time? Don't worry, Rustlings was made for beginners! We are
+going to teach you a lot of things about Rust, but before we can get
+started, here's a couple of notes about how Rustlings operates:

-Let's make sure you're up to speed:
- You have Rust installed, preferably via `rustup`
- You have `~/.cargo/bin` added to your PATH variable
- You have cloned this repository (https://github.com/rust-lang/rustlings)
- You have installed Rust language support for your editor
- You have locally installed the `rustlings` command by running an
-  installation script or manually executing:
+1. The central concept behind Rustlings is that you solve exercises. These
+   exercises usually have some sort of syntax error in them, which will cause
+   them to fail compilation or testing. Sometimes there's a logic error instead
+   of a syntax error. No matter what error, it's your job to find it and fix it!
+   You'll know when you fixed it because then, the exercise will compile and
+   Rustlings will be able to move on to the next exercise.
+2. If you run Rustlings in watch mode (which we recommend), it'll automatically
+   start with the first exercise. Don't get confused by an error message popping
+   up as soon as you run Rustlings! This is part of the exercise that you're
+   supposed to solve, so open the exercise file in an editor and start your
+   detective work!
+3. If you're stuck on an exercise, there is a helpful hint you can view by typing
+   'hint' (in watch mode), or running `rustlings hint myexercise`.
+4. If an exercise doesn't make sense to you, feel free to open an issue on GitHub!
+   (https://github.com/rust-lang/rustlings/issues/new). We look at every issue,
+   and sometimes, other learners do too so you can help each other out!

-cargo install --force --path .
-
-If you've done all of this (or even most of it), congrats! You're ready
-to start working with Rust.
-
-To get started, run `rustlings watch` in order to get the first exercise.
-Make sure to have your editor open!
+Got all that? Great! To get started, run `rustlings watch` in order to get the first
+exercise. Make sure to have your editor open!
--- a/exercises/README.md
+++ b/exercises/README.md
@@ -0,0 +1,24 @@
+# Exercise to Book Chapter mapping
+
+| Exercise               | Book Chapter |
+|------------------------|--------------|
+| variables              | §3.1          |
+| functions              | §3.3          |
+| if                     | §3.5          |
+| move_semantics         | §4.1          |
+| primitive_types        | §4.3          |
+| structs                | §5.1          |
+| enums                  | §6            |
+| modules                | §7.2          |
+| collections            | §8.1          |
+| strings                | §8.2          |
+| error_handling         | §9            |
+| generics               | §10           |
+| option                 | §10.1         |
+| traits                 | §10.2         |
+| tests                  | §11.1         |
+| standard_library_types | §13.2         |
+| threads                | §16.1         |
+| macros                 | §19.6         |
+| clippy                 | n/a           |
+| conversions            | n/a           |
--- a/exercises/clippy/README.md
+++ b/exercises/clippy/README.md
@@ -1,8 +1,10 @@
-### Clippy
+# Clippy

 The Clippy tool is a collection of lints to analyze your code so you can catch common mistakes and improve your Rust code.

 If you used the installation script for Rustlings, Clippy should be already installed.
 If not you can install it manually via `rustup component add clippy`.

-For more information about Clippy lints, please see [their documentation page](https://rust-lang.github.io/rust-clippy/master/).
+## Further information
+
+- [GitHub Repository](https://github.com/rust-lang/rust-clippy).
--- a/exercises/clippy/clippy1.rs
+++ b/exercises/clippy/clippy1.rs
@@ -2,6 +2,8 @@
 // The Clippy tool is a collection of lints to analyze your code
 // so you can catch common mistakes and improve your Rust code.
 //
+// For these exercises the code will fail to compile when there are clippy warnings
+// check clippy's suggestions from the output to solve the exercise.
 // Execute `rustlings hint clippy1` for hints :)

 // I AM NOT DONE
--- a/exercises/collections/README.md
+++ b/exercises/collections/README.md
@@ -0,0 +1,22 @@
+# Collections
+
+Rust’s standard library includes a number of very useful data
+structures called collections. Most other data types represent one
+specific value, but collections can contain multiple values. Unlike
+the built-in array and tuple types, the data these collections point
+to is stored on the heap, which means the amount of data does not need
+to be known at compile time and can grow or shrink as the program
+runs.
+
+This exercise will get you familiar with two fundamental data
+structures that are used very often in Rust programs:
+
+* A *vector* allows you to store a variable number of values next to
+  each other.
+* A *hash map* allows you to associate a value with a particular key.
+  You may also know this by the names [*unordered map* in C++](https://en.cppreference.com/w/cpp/container/unordered_map), 
+  [*dictionary* in Python](https://docs.python.org/3/tutorial/datastructures.html#dictionaries) or an *associative array* in other languages.
+
+## Further information
+
+- [Storing Lists of Values with Vectors](https://doc.rust-lang.org/stable/book/ch08-01-vectors.html)
--- a/exercises/collections/hashmap1.rs
+++ b/exercises/collections/hashmap1.rs
@@ -0,0 +1,44 @@
+// hashmap1.rs
+// A basket of fruits in the form of a hash map needs to be defined.
+// The key represents the name of the fruit and the value represents
+// how many of that particular fruit is in the basket. You have to put
+// at least three different types of fruits (e.g apple, banana, mango)
+// in the basket and the total count of all the fruits should be at
+// least five.
+//
+// Make me compile and pass the tests!
+//
+// Execute the command `rustlings hint hashmap1` if you need
+// hints.
+
+// I AM NOT DONE
+
+use std::collections::HashMap;
+
+fn fruit_basket() -> HashMap<String, u32> {
+    let mut basket = // TODO: declare your hash map here.
+
+    // Two bananas are already given for you :)
+    basket.insert(String::from("banana"), 2);
+
+    // TODO: Put more fruits in your basket here.
+
+    basket
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn at_least_three_types_of_fruits() {
+        let basket = fruit_basket();
+        assert!(basket.len() >= 3);
+    }
+
+    #[test]
+    fn at_least_five_fruits() {
+        let basket = fruit_basket();
+        assert!(basket.values().sum::<u32>() >= 5);
+    }
+}
--- a/exercises/collections/hashmap2.rs
+++ b/exercises/collections/hashmap2.rs
@@ -0,0 +1,81 @@
+// hashmap2.rs
+
+// A basket of fruits in the form of a hash map is given. The key
+// represents the name of the fruit and the value represents how many
+// of that particular fruit is in the basket. You have to put *MORE
+// THAN 11* fruits in the basket. Three types of fruits - Apple (4),
+// Mango (2) and Lychee (5) are already given in the basket. You are
+// not allowed to insert any more of these fruits!
+//
+// Make me pass the tests!
+//
+// Execute the command `rustlings hint hashmap2` if you need
+// hints.
+
+// I AM NOT DONE
+
+use std::collections::HashMap;
+
+#[derive(Hash, PartialEq, Eq)]
+enum Fruit {
+    Apple,
+    Banana,
+    Mango,
+    Lychee,
+    Pineapple,
+}
+
+fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
+    let fruit_kinds = vec![
+        Fruit::Apple,
+        Fruit::Banana,
+        Fruit::Mango,
+        Fruit::Lychee,
+        Fruit::Pineapple,
+    ];
+
+    for fruit in fruit_kinds {
+        // TODO: Put new fruits if not already present. Note that you
+        // are not allowed to put any type of fruit that's already
+        // present!
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn get_fruit_basket() -> HashMap<Fruit, u32> {
+        let mut basket = HashMap::<Fruit, u32>::new();
+        basket.insert(Fruit::Apple, 4);
+        basket.insert(Fruit::Mango, 2);
+        basket.insert(Fruit::Lychee, 5);
+
+        basket
+    }
+
+    #[test]
+    fn test_given_fruits_are_not_modified() {
+        let mut basket = get_fruit_basket();
+        fruit_basket(&mut basket);
+        assert_eq!(*basket.get(&Fruit::Apple).unwrap(), 4);
+        assert_eq!(*basket.get(&Fruit::Mango).unwrap(), 2);
+        assert_eq!(*basket.get(&Fruit::Lychee).unwrap(), 5);
+    }
+
+    #[test]
+    fn at_least_five_types_of_fruits() {
+        let mut basket = get_fruit_basket();
+        fruit_basket(&mut basket);
+        let count_fruit_kinds = basket.len();
+        assert!(count_fruit_kinds >= 5);
+    }
+
+    #[test]
+    fn greater_than_eleven_fruits() {
+        let mut basket = get_fruit_basket();
+        fruit_basket(&mut basket);
+        let count = basket.values().sum::<u32>();
+        assert!(count > 11);
+    }
+}
--- a/exercises/collections/vec1.rs
+++ b/exercises/collections/vec1.rs
@@ -0,0 +1,25 @@
+// vec1.rs
+// Your task is to create a `Vec` which holds the exact same elements
+// as in the array `a`.
+// Make me compile and pass the test!
+// Execute the command `rustlings hint vec1` if you need hints.
+
+// I AM NOT DONE
+
+fn array_and_vec() -> ([i32; 4], Vec<i32>) {
+    let a = [10, 20, 30, 40]; // a plain array
+    let v = // TODO: declare your vector here with the macro for vectors
+
+    (a, v)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_array_and_vec_similarity() {
+        let (a, v) = array_and_vec();
+        assert_eq!(a, v[..]);
+    }
+}
--- a/exercises/collections/vec2.rs
+++ b/exercises/collections/vec2.rs
@@ -0,0 +1,33 @@
+// vec2.rs
+// A Vec of even numbers is given. Your task is to complete the loop
+// so that each number in the Vec is multiplied by 2.
+//
+// Make me pass the test!
+//
+// Execute the command `rustlings hint vec2` if you need
+// hints.
+
+// I AM NOT DONE
+
+fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
+    for i in v.iter_mut() {
+        // TODO: Fill this up so that each element in the Vec `v` is
+        // multiplied by 2.
+    }
+
+    // At this point, `v` should be equal to [4, 8, 12, 16, 20].
+    v
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_vec_loop() {
+        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
+        let ans = vec_loop(v.clone());
+
+        assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
+    }
+}
--- a/exercises/conversions/README.md
+++ b/exercises/conversions/README.md
@@ -1,5 +1,4 @@
-### Type conversions
-
+# Type conversions

 Rust offers a multitude of ways to convert a value of a given type into another type.

@@ -15,6 +14,8 @@ Furthermore, the `std::str` module offers a trait called [`FromStr`](https://doc

 These should be the main ways ***within the standard library*** to convert data into your desired types.

-#### Book Sections
+## Further information

-These are not directly covered in the book, but the standard library has great documentation for [conversions here](https://doc.rust-lang.org/std/convert/index.html). The `FromStr` trait is also covered [here](https://doc.rust-lang.org/std/str/trait.FromStr.html).
+These are not directly covered in the book, but the standard library has a great documentation for it.
+- [conversions](https://doc.rust-lang.org/std/convert/index.html)
+- [`FromStr` trait](https://doc.rust-lang.org/std/str/trait.FromStr.html)
--- a/exercises/conversions/as_ref_mut.rs
+++ b/exercises/conversions/as_ref_mut.rs
@@ -3,6 +3,7 @@
 // and https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.

 // I AM NOT DONE
+
 // Obtain the number of bytes (not characters) in the given argument
 // Add the AsRef trait appropriately as a trait bound
 fn byte_counter<T>(arg: T) -> usize {
@@ -36,4 +37,16 @@ mod tests {
        let s = "Cafe au lait";
        assert_eq!(char_counter(s), byte_counter(s));
    }
+
+    #[test]
+    fn different_counts_using_string() {
+        let s = String::from("Café au lait");
+        assert_ne!(char_counter(s.clone()), byte_counter(s));
+    }
+
+    #[test]
+    fn same_counts_using_string() {
+        let s = String::from("Cafe au lait");
+        assert_eq!(char_counter(s.clone()), byte_counter(s));
+    }
 }
--- a/exercises/conversions/from_into.rs
+++ b/exercises/conversions/from_into.rs
@@ -18,7 +18,6 @@ impl Default for Person {
    }
 }

-// I AM NOT DONE
 // Your task is to complete this implementation
 // in order for the line `let p = Person::from("Mark,20")` to compile
 // Please note that you'll need to parse the age component into a `usize`
@@ -29,9 +28,13 @@ impl Default for Person {
 // 1. If the length of the provided string is 0, then return the default of Person
 // 2. Split the given string on the commas present in it
 // 3. Extract the first element from the split operation and use it as the name
-// 4. Extract the other element from the split operation and parse it into a `usize` as the age
+// 4. If the name is empty, then return the default of Person
+// 5. Extract the other element from the split operation and parse it into a `usize` as the age
 // If while parsing the age, something goes wrong, then return the default of Person
-// Otherwise, then return an instantiated Person onject with the results
+// Otherwise, then return an instantiated Person object with the results
+
+// I AM NOT DONE
+
 impl From<&str> for Person {
    fn from(s: &str) -> Person {
    }
@@ -72,9 +75,58 @@ mod tests {
    }
    #[test]
    fn test_bad_age() {
-        // Test that "Mark.twenty" will return the default person due to an error in parsing age
+        // Test that "Mark,twenty" will return the default person due to an error in parsing age
        let p = Person::from("Mark,twenty");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }
+
+    #[test]
+    fn test_missing_comma_and_age() {
+        let p: Person = Person::from("Mark");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_age() {
+        let p: Person = Person::from("Mark,");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_name() {
+        let p: Person = Person::from(",1");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_name_and_age() {
+        let p: Person = Person::from(",");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_missing_name_and_invalid_age() {
+        let p: Person = Person::from(",one");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_trailing_comma() {
+        let p: Person = Person::from("Mike,32,");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
+
+    #[test]
+    fn test_trailing_comma_and_some_string() {
+        let p: Person = Person::from("Mike,32,man");
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 30);
+    }
 }
--- a/exercises/conversions/from_str.rs
+++ b/exercises/conversions/from_str.rs
@@ -2,6 +2,7 @@
 // Additionally, upon implementing FromStr, you can use the `parse` method
 // on strings to generate an object of the implementor type.
 // You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
+use std::error;
 use std::str::FromStr;

 #[derive(Debug)]
@@ -11,15 +12,19 @@ struct Person {
 }

 // I AM NOT DONE
+
 // Steps:
-// 1. If the length of the provided string is 0, then return an error
+// 1. If the length of the provided string is 0, an error should be returned
 // 2. Split the given string on the commas present in it
-// 3. Extract the first element from the split operation and use it as the name
-// 4. Extract the other element from the split operation and parse it into a `usize` as the age
-// If while parsing the age, something goes wrong, then return an error
-// Otherwise, then return a Result of a Person object
+// 3. Only 2 elements should be returned from the split, otherwise return an error
+// 4. Extract the first element from the split operation and use it as the name
+// 5. Extract the other element from the split operation and parse it into a `usize` as the age
+//    with something like `"4".parse::<usize>()`
+// 5. If while extracting the name and the age something goes wrong, an error should be returned
+// If everything goes well, then return a Result of a Person object
+
 impl FromStr for Person {
-    type Err = String;
+    type Err = Box<dyn error::Error>;
    fn from_str(s: &str) -> Result<Person, Self::Err> {
    }
 }
@@ -39,11 +44,49 @@ mod tests {
    }
    #[test]
    fn good_input() {
-        assert!("John,32".parse::<Person>().is_ok());
+        let p = "John,32".parse::<Person>();
+        assert!(p.is_ok());
+        let p = p.unwrap();
+        assert_eq!(p.name, "John");
+        assert_eq!(p.age, 32);
    }
    #[test]
-    #[should_panic]
    fn missing_age() {
-        "John".parse::<Person>().unwrap();
+        assert!("John,".parse::<Person>().is_err());
    }
-}
+
+    #[test]
+    fn invalid_age() {
+        assert!("John,twenty".parse::<Person>().is_err());
+    }
+
+    #[test]
+    fn missing_comma_and_age() {
+        assert!("John".parse::<Person>().is_err());
+    }
+
+    #[test]
+    fn missing_name() {
+        assert!(",1".parse::<Person>().is_err());
+    }
+
+    #[test]
+    fn missing_name_and_age() {
+        assert!(",".parse::<Person>().is_err());
+    }
+
+    #[test]
+    fn missing_name_and_invalid_age() {
+        assert!(",one".parse::<Person>().is_err());
+    }
+
+    #[test]
+    fn trailing_comma() {
+        assert!("John,32,".parse::<Person>().is_err());
+    }
+
+    #[test]
+    fn trailing_comma_and_some_string() {
+        assert!("John,32,man".parse::<Person>().is_err());
+    }
+}
--- a/exercises/conversions/try_from_into.rs
+++ b/exercises/conversions/try_from_into.rs
@@ -2,70 +2,157 @@
 // Basically, this is the same as From. The main difference is that this should return a Result type
 // instead of the target type itself.
 // You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
-use std::convert::{TryInto, TryFrom};
+use std::convert::{TryFrom, TryInto};
+use std::error;

-#[derive(Debug)]
-struct Person {
-    name: String,
-    age: usize,
+#[derive(Debug, PartialEq)]
+struct Color {
+    red: u8,
+    green: u8,
+    blue: u8,
 }

 // I AM NOT DONE
+
 // Your task is to complete this implementation
-// in order for the line `let p = Person::try_from("Mark,20")` to compile
-// and return an Ok result of inner type Person.
-// Please note that you'll need to parse the age component into a `usize`
-// with something like `"4".parse::<usize>()`. The outcome of this needs to
-// be handled appropriately.
+// and return an Ok result of inner type Color.
+// You need to create an implementation for a tuple of three integers,
+// an array of three integers and a slice of integers.
 //
-// Steps:
-// 1. If the length of the provided string is 0, then return an error
-// 2. Split the given string on the commas present in it
-// 3. Extract the first element from the split operation and use it as the name
-// 4. Extract the other element from the split operation and parse it into a `usize` as the age
-// If while parsing the age, something goes wrong, then return an error
-// Otherwise, then return a Result of a Person object
-impl TryFrom<&str> for Person {
-    type Error = String;
-    fn try_from(s: &str) -> Result<Self, Self::Error> {
-    }
+// Note that the implementation for tuple and array will be checked at compile time,
+// but the slice implementation needs to check the slice length!
+// Also note that correct RGB color values must be integers in the 0..=255 range.
+
+// Tuple implementation
+impl TryFrom<(i16, i16, i16)> for Color {
+    type Error = Box<dyn error::Error>;
+    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {}
+}
+
+// Array implementation
+impl TryFrom<[i16; 3]> for Color {
+    type Error = Box<dyn error::Error>;
+    fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {}
+}
+
+// Slice implementation
+impl TryFrom<&[i16]> for Color {
+    type Error = Box<dyn error::Error>;
+    fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {}
 }

 fn main() {
    // Use the `from` function
-    let p1 = Person::try_from("Mark,20");
-    // Since From is implemented for Person, we should be able to use Into
-    let p2: Result<Person, _> = "Gerald,70".try_into();
-    println!("{:?}", p1);
-    println!("{:?}", p2);
+    let c1 = Color::try_from((183, 65, 14));
+    println!("{:?}", c1);
+
+    // Since From is implemented for Color, we should be able to use Into
+    let c2: Result<Color, _> = [183, 65, 14].try_into();
+    println!("{:?}", c2);
+
+    let v = vec![183, 65, 14];
+    // With slice we should use `from` function
+    let c3 = Color::try_from(&v[..]);
+    println!("{:?}", c3);
+    // or take slice within round brackets and use Into
+    let c4: Result<Color, _> = (&v[..]).try_into();
+    println!("{:?}", c4);
 }

 #[cfg(test)]
 mod tests {
    use super::*;
+
    #[test]
-    fn test_bad_convert() {
-        // Test that John is returned when bad string is provided
-        let p = Person::try_from("");
-        assert!(p.is_err());
+    fn test_tuple_out_of_range_positive() {
+        assert!(Color::try_from((256, 1000, 10000)).is_err());
    }
    #[test]
-    fn test_good_convert() {
-        // Test that "Mark,20" works
-        let p = Person::try_from("Mark,20");
-        assert!(p.is_ok());
-        let p = p.unwrap();
-        assert_eq!(p.name, "Mark");
-        assert_eq!(p.age, 20);
+    fn test_tuple_out_of_range_negative() {
+        assert!(Color::try_from((-1, -10, -256)).is_err());
    }
    #[test]
-    #[should_panic]
-    fn test_panic_empty_input() {
-        let p: Person = "".try_into().unwrap();
+    fn test_tuple_sum() {
+        assert!(Color::try_from((-1, 255, 255)).is_err());
    }
    #[test]
-    #[should_panic]
-    fn test_panic_bad_age() {
-        let p = Person::try_from("Mark,twenty").unwrap();
+    fn test_tuple_correct() {
+        let c: Result<Color, _> = (183, 65, 14).try_into();
+        assert!(c.is_ok());
+        assert_eq!(
+            c.unwrap(),
+            Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            }
+        );
    }
-}
+    #[test]
+    fn test_array_out_of_range_positive() {
+        let c: Result<Color, _> = [1000, 10000, 256].try_into();
+        assert!(c.is_err());
+    }
+    #[test]
+    fn test_array_out_of_range_negative() {
+        let c: Result<Color, _> = [-10, -256, -1].try_into();
+        assert!(c.is_err());
+    }
+    #[test]
+    fn test_array_sum() {
+        let c: Result<Color, _> = [-1, 255, 255].try_into();
+        assert!(c.is_err());
+    }
+    #[test]
+    fn test_array_correct() {
+        let c: Result<Color, _> = [183, 65, 14].try_into();
+        assert!(c.is_ok());
+        assert_eq!(
+            c.unwrap(),
+            Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            }
+        );
+    }
+    #[test]
+    fn test_slice_out_of_range_positive() {
+        let arr = [10000, 256, 1000];
+        assert!(Color::try_from(&arr[..]).is_err());
+    }
+    #[test]
+    fn test_slice_out_of_range_negative() {
+        let arr = [-256, -1, -10];
+        assert!(Color::try_from(&arr[..]).is_err());
+    }
+    #[test]
+    fn test_slice_sum() {
+        let arr = [-1, 255, 255];
+        assert!(Color::try_from(&arr[..]).is_err());
+    }
+    #[test]
+    fn test_slice_correct() {
+        let v = vec![183, 65, 14];
+        let c: Result<Color, _> = Color::try_from(&v[..]);
+        assert!(c.is_ok());
+        assert_eq!(
+            c.unwrap(),
+            Color {
+                red: 183,
+                green: 65,
+                blue: 14
+            }
+        );
+    }
+    #[test]
+    fn test_slice_excess_length() {
+        let v = vec![0, 0, 0, 0];
+        assert!(Color::try_from(&v[..]).is_err());
+    }
+    #[test]
+    fn test_slice_insufficient_length() {
+        let v = vec![0, 0];
+        assert!(Color::try_from(&v[..]).is_err());
+    }
+}
--- a/exercises/conversions/using_as.rs
+++ b/exercises/conversions/using_as.rs
@@ -1,17 +1,28 @@
 // Type casting in Rust is done via the usage of the `as` operator.
 // Please note that the `as` operator is not only used when type casting.
 // It also helps with renaming imports.
+//
+// The goal is to make sure that the division does not fail to compile
+// and returns the proper type.

 // I AM NOT DONE
-// The goal is to make sure that the division does not fail to compile
+
 fn average(values: &[f64]) -> f64 {
-    let total = values
-        .iter()
-        .fold(0.0, |a, b| a + b);
+    let total = values.iter().fold(0.0, |a, b| a + b);
    total / values.len()
 }

 fn main() {
    let values = [3.5, 0.3, 13.0, 11.7];
    println!("{}", average(&values));
-}
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn returns_proper_type_and_value() {
+        assert_eq!(average(&[3.5, 0.3, 13.0, 11.7]), 7.125);
+    }
+}
--- a/exercises/enums/README.md
+++ b/exercises/enums/README.md
@@ -1,10 +1,10 @@
-### Enums
+# Enums

-Rust allows you to define types called "enums" which enumerate possible values. 
+Rust allows you to define types called "enums" which enumerate possible values.
 Enums are a feature in many languages, but their capabilities differ in each language. Rust’s enums are most similar to algebraic data types in functional languages, such as F#, OCaml, and Haskell.
-Useful in combination with enums is Rust's "pattern matching" facility, which makes it easy to run different code for different values of an enumeration.  
+Useful in combination with enums is Rust's "pattern matching" facility, which makes it easy to run different code for different values of an enumeration.

-#### Book Sections
+## Further information

 - [Enums](https://doc.rust-lang.org/book/ch06-00-enums.html)
 - [Pattern syntax](https://doc.rust-lang.org/book/ch18-03-pattern-syntax.html)
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -16,10 +16,10 @@ impl Message {

 fn main() {
    let messages = [
-        Message::Move{ x: 10, y: 30 },
+        Message::Move { x: 10, y: 30 },
        Message::Echo(String::from("hello world")),
        Message::ChangeColor(200, 255, 255),
-        Message::Quit
+        Message::Quit,
    ];

    for message in &messages {
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -9,13 +9,13 @@ enum Message {

 struct Point {
    x: u8,
-    y: u8
+    y: u8,
 }

 struct State {
    color: (u8, u8, u8),
    position: Point,
-    quit: bool
+    quit: bool,
 }

 impl State {
@@ -46,14 +46,14 @@ mod tests {

    #[test]
    fn test_match_message_call() {
-        let mut state = State{
+        let mut state = State {
            quit: false,
-            position: Point{ x: 0, y: 0 },
-            color: (0, 0, 0)
+            position: Point { x: 0, y: 0 },
+            color: (0, 0, 0),
        };
-        state.process(Message::ChangeColor(255, 0, 255));
+        state.process(Message::ChangeColor((255, 0, 255)));
        state.process(Message::Echo(String::from("hello world")));
-        state.process(Message::Move{ x: 10, y: 15 });
+        state.process(Message::Move(Point { x: 10, y: 15 }));
        state.process(Message::Quit);

        assert_eq!(state.color, (255, 0, 255));
@@ -61,5 +61,4 @@ mod tests {
        assert_eq!(state.position.y, 15);
        assert_eq!(state.quit, true);
    }
-
 }
--- a/exercises/error_handling/README.md
+++ b/exercises/error_handling/README.md
@@ -1,5 +1,11 @@
-For this exercise check out the sections:
- [Error Handling](https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html) 
- [Generics](https://doc.rust-lang.org/book/ch10-01-syntax.html) 
+# Error handling
+Most errors aren’t serious enough to require the program to stop entirely. 
+Sometimes, when a function fails, it’s for a reason that you can easily interpret and respond to.
+For example, if you try to open a file and that operation fails because the file doesn’t exist, you might want to create the file instead of terminating the process.

-of the Rust Book.
+## Further information
+
+- [Error Handling](https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html)
+- [Generics](https://doc.rust-lang.org/book/ch10-01-syntax.html)
+- [Result](https://doc.rust-lang.org/rust-by-example/error/result.html)
+- [Boxing errors](https://doc.rust-lang.org/rust-by-example/error/multiple_error_types/boxing_errors.html)
--- a/exercises/error_handling/errorsn.rs
+++ b/exercises/error_handling/errorsn.rs
@@ -2,8 +2,10 @@
 // This is a bigger error exercise than the previous ones!
 // You can do it! :)
 //
-// Edit the `read_and_validate` function so that it compiles and
-// passes the tests... so many things could go wrong!
+// Edit the `read_and_validate` function ONLY. Don't create any Errors
+// that do not already exist.
+//
+// So many things could go wrong!
 //
 // - Reading from stdin could produce an io::Error
 // - Parsing the input could produce a num::ParseIntError
@@ -30,6 +32,10 @@ fn read_and_validate(b: &mut dyn io::BufRead) -> Result<PositiveNonzeroInteger,
    answer
 }

+//
+// Nothing below this needs to be modified
+//
+
 // This is a test helper function that turns a &str into a BufReader.
 fn test_with_str(s: &str) -> Result<PositiveNonzeroInteger, Box<dyn error::Error>> {
    let mut b = io::BufReader::new(s.as_bytes());
@@ -100,15 +106,12 @@ enum CreationError {

 impl fmt::Display for CreationError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.write_str((self as &dyn error::Error).description())
+        let description = match *self {
+            CreationError::Negative => "Number is negative",
+            CreationError::Zero => "Number is zero",
+        };
+        f.write_str(description)
    }
 }

-impl error::Error for CreationError {
-    fn description(&self) -> &str {
-        match *self {
-            CreationError::Negative => "Negative",
-            CreationError::Zero => "Zero",
-        }
-    }
-}
+impl error::Error for CreationError {}
--- a/exercises/error_handling/option1.rs
+++ b/exercises/error_handling/option1.rs
@@ -1,31 +0,0 @@
-// option1.rs
-// This example panics because the second time it calls `pop`, the `vec`
-// is empty, so `pop` returns `None`, and `unwrap` panics if it's called
-// on `None`. Handle this in a more graceful way than calling `unwrap`!
-// Execute `rustlings hint option1` for hints :)
-
-// I AM NOT DONE
-
-pub fn pop_too_much() -> bool {
-    let mut list = vec![3];
-
-    let last = list.pop().unwrap();
-    println!("The last item in the list is {:?}", last);
-
-    let second_to_last = list.pop().unwrap();
-    println!(
-        "The second-to-last item in the list is {:?}",
-        second_to_last
-    );
-    true
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn should_not_panic() {
-        assert!(pop_too_much());
-    }
-}
--- a/exercises/functions/README.md
+++ b/exercises/functions/README.md
@@ -1,7 +1,7 @@
-### Functions
+# Functions

 Here, you'll learn how to write functions and how Rust's compiler can trace things way back.

-#### Book Sections
+## Further information

 - [How Functions Work](https://doc.rust-lang.org/book/ch03-03-how-functions-work.html)
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -7,7 +7,7 @@ fn main() {
    call_me(3);
 }

-fn call_me(num) {
+fn call_me(num:) {
    for i in 0..num {
        println!("Ring! Call number {}", i + 1);
    }
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -7,7 +7,7 @@ fn main() {
    call_me();
 }

-fn call_me(num: i32) {
+fn call_me(num: u32) {
    for i in 0..num {
        println!("Ring! Call number {}", i + 1);
    }
--- a/exercises/generics/README.md
+++ b/exercises/generics/README.md
@@ -1,7 +1,11 @@
-### Generics
+# Generics

-In this section you'll learn about saving yourself many lines of code with generics!
+Generics is the topic of generalizing types and functionalities to broader cases.
+This is extremely useful for reducing code duplication in many ways, but can call for rather involving syntax.
+Namely, being generic requires taking great care to specify over which types a generic type is actually considered valid.
+The simplest and most common use of generics is for type parameters.

-### Book Sections
+## Further information

- [Generic Data Types](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html)
+- [Generic Data Types](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html)
+- [Bounds](https://doc.rust-lang.org/rust-by-example/generics/bounds.html)
--- a/exercises/generics/generics1.rs
+++ b/exercises/generics/generics1.rs
@@ -1,4 +1,4 @@
-// This shopping list program isn't compiling! 
+// This shopping list program isn't compiling!
 // Use your knowledge of generics to fix it.

 // I AM NOT DONE
@@ -7,4 +7,3 @@ fn main() {
    let mut shopping_list: Vec<?> = Vec::new();
    shopping_list.push("milk");
 }
-
--- a/exercises/generics/generics2.rs
+++ b/exercises/generics/generics2.rs
@@ -2,11 +2,12 @@
 // Rewrite it using generics so that it supports wrapping ANY type.

 // I AM NOT DONE
-struct Wrapper<u32> {
-    value: u32
+
+struct Wrapper {
+    value: u32,
 }

-impl<u32> Wrapper<u32> {
+impl Wrapper {
    pub fn new(value: u32) -> Self {
        Wrapper { value }
    }
@@ -18,13 +19,11 @@ mod tests {

    #[test]
    fn store_u32_in_wrapper() {
-        assert_eq!(Wrapper::new(42).value,  42);
+        assert_eq!(Wrapper::new(42).value, 42);
    }

    #[test]
    fn store_str_in_wrapper() {
-        // TODO: Delete this assert and uncomment the one  below once you have  finished the exercise.
-        assert!(false);
-        // assert_eq!(Wrapper::new("Foo").value, "Foo");
+        assert_eq!(Wrapper::new("Foo").value, "Foo");
    }
-}
+}
--- a/exercises/generics/generics3.rs
+++ b/exercises/generics/generics3.rs
@@ -1,12 +1,17 @@
-// An imaginary magical school has a new report card generation system written in rust!
-// Currently the system only supports creating report cards where the student's grade 
-// is represented numerically (e.g. 1.0 -> 5.5). However, the school also issues alphabetical grades
-// (A+ -> F-) and needs to be able to print both types of report card!
+// An imaginary magical school has a new report card generation system written in Rust!
+// Currently the system only supports creating report cards where the student's grade
+// is represented numerically (e.g. 1.0 -> 5.5).
+// However, the school also issues alphabetical grades (A+ -> F-) and needs
+// to be able to print both types of report card!

-// Make the necessary code changes to support alphabetical report cards, thereby making the second
-// test pass.
+// Make the necessary code changes in the struct ReportCard and the impl block
+// to support alphabetical report cards. Change the Grade in the second test to "A+"
+// to show that your changes allow alphabetical grades.
+
+// Execute 'rustlings hint generics3' for hints!

 // I AM NOT DONE
+
 pub struct ReportCard {
    pub grade: f32,
    pub student_name: String,
@@ -15,7 +20,8 @@ pub struct ReportCard {

 impl ReportCard {
    pub fn print(&self) -> String {
-        format!("{} ({}) - achieved a grade of {}", &self.student_name, &self.student_age, &self.grade)
+        format!("{} ({}) - achieved a grade of {}",
+            &self.student_name, &self.student_age, &self.grade)
    }
 }

@@ -26,21 +32,27 @@ mod tests {
    #[test]
    fn generate_numeric_report_card() {
        let report_card = ReportCard {
-            grade: 2.1, 
-            student_name: "Tom Wriggle".to_string(), 
+            grade: 2.1,
+            student_name: "Tom Wriggle".to_string(),
            student_age: 12,
        };
-        assert_eq!(report_card.print(), "Tom Wriggle (12) - achieved a grade of 2.1");
+        assert_eq!(
+            report_card.print(),
+            "Tom Wriggle (12) - achieved a grade of 2.1"
+        );
    }

    #[test]
    fn generate_alphabetic_report_card() {
        // TODO: Make sure to change the grade here after you finish the exercise.
        let report_card = ReportCard {
-            grade: 2.1, 
-            student_name: "Gary Plotter".to_string(), 
+            grade: 2.1,
+            student_name: "Gary Plotter".to_string(),
            student_age: 11,
        };
-        assert_eq!(report_card.print(), "Gary Plotter (11) - achieved a grade of A+");
+        assert_eq!(
+            report_card.print(),
+            "Gary Plotter (11) - achieved a grade of A+"
+        );
    }
-}
+}
--- a/exercises/if/README.md
+++ b/exercises/if/README.md
@@ -1,7 +1,7 @@
-### If
+# If

 `if`, the most basic type of control flow, is what you'll learn here.

-#### Book Sections
+## Further information

 - [Control Flow - if expressions](https://doc.rust-lang.org/book/ch03-05-control-flow.html#if-expressions)
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -0,0 +1,36 @@
+// if2.rs
+
+// Step 1: Make me compile!
+// Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
+// Execute the command `rustlings hint if2` if you want a hint :)
+
+// I AM NOT DONE
+
+pub fn fizz_if_foo(fizzish: &str) -> &str {
+    if fizzish == "fizz" {
+        "foo"
+    } else {
+        1
+    }
+}
+
+// No test changes needed!
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn foo_for_fizz() {
+        assert_eq!(fizz_if_foo("fizz"), "foo")
+    }
+
+    #[test]
+    fn bar_for_fuzz() {
+        assert_eq!(fizz_if_foo("fuzz"), "bar")
+    }
+
+    #[test]
+    fn default_to_baz() {
+        assert_eq!(fizz_if_foo("literally anything"), "baz")
+    }
+}
--- a/exercises/macros/README.md
+++ b/exercises/macros/README.md
@@ -1,10 +1,10 @@
-### Macros
+# Macros

 Rust's macro system is very powerful, but also kind of difficult to wrap your
 head around. We're not going to teach you how to write your own fully-featured
-modules, instead we'll show you how to use and create them.
+macros. Instead, we'll show you how to use and create them.

-#### Book Sections
+## Further information

 - [Macros](https://doc.rust-lang.org/book/ch19-06-macros.html)
 - [The Little Book of Rust Macros](https://danielkeep.github.io/tlborm/book/index.html)
--- a/exercises/modules/README.md
+++ b/exercises/modules/README.md
@@ -1,7 +1,7 @@
-### Modules
+# Modules

 In this section we'll give you an introduction to Rust's module system.

-#### Book Sections
+## Further information

 - [The Module System](https://doc.rust-lang.org/book/ch07-02-defining-modules-to-control-scope-and-privacy.html)
--- a/exercises/move_semantics/README.md
+++ b/exercises/move_semantics/README.md
@@ -1,8 +1,8 @@
-### Move Semantics
+# Move Semantics

 These exercises are adapted from [pnkfelix](https://github.com/pnkfelix)'s [Rust Tutorial](https://pnkfelix.github.io/rust-examples-icfp2014/) -- Thank you Felix!!!

-#### Book Sections
+## Further information

 For this section, the book links are especially important.

--- a/exercises/move_semantics/move_semantics4.rs
+++ b/exercises/move_semantics/move_semantics4.rs
@@ -1,6 +1,6 @@
 // move_semantics4.rs
 // Refactor this code so that instead of having `vec0` and creating the vector
-// in `fn main`, we instead create it within `fn fill_vec` and transfer the
+// in `fn main`, we create it within `fn fill_vec` and transfer the
 // freshly created vector from fill_vec to its caller.
 // Execute `rustlings hint move_semantics4` for hints!

@@ -18,7 +18,7 @@ fn main() {
    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }

-// `fill_vec()` no longer take `vec: Vec<i32>` as argument
+// `fill_vec()` no longer takes `vec: Vec<i32>` as argument
 fn fill_vec() -> Vec<i32> {
    let mut vec = vec;

--- a/exercises/option/README.md
+++ b/exercises/option/README.md
@@ -1,8 +1,17 @@
-### Option
+# Option

-#### Book Sections
+Type Option represents an optional value: every Option is either Some and contains a value, or None, and does not. 
+Option types are very common in Rust code, as they have a number of uses:
+- Initial values
+- Return values for functions that are not defined over their entire input range (partial functions)
+- Return value for otherwise reporting simple errors, where None is returned on error
+- Optional struct fields
+- Struct fields that can be loaned or "taken"
+- Optional function arguments
+- Nullable pointers
+- Swapping things out of difficult situations

-To learn about Option<T>, check out these links:
+## Further Information

 - [Option Enum Format](https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-enum-definitions)
 - [Option Module Documentation](https://doc.rust-lang.org/std/option/)
--- a/exercises/option/option1.rs
+++ b/exercises/option/option1.rs
@@ -15,9 +15,9 @@ fn main() {
    let mut numbers: [Option<u16>; 5];
    for iter in 0..5 {
        let number_to_add: u16 = {
-            ((iter * 5) + 2) / (4 * 16)
+            ((iter * 1235) + 2) / (4 * 16)
        };

-        numbers[iter] = number_to_add;
+        numbers[iter as usize] = number_to_add;
    }
 }
--- a/exercises/option/option2.rs
+++ b/exercises/option/option2.rs
@@ -4,22 +4,22 @@
 // I AM NOT DONE

 fn main() {
-    let optional_value = Some(String::from("rustlings"));
-    // Make this an if let statement whose value is "Some" type
-    value = optional_value {
-        println!("the value of optional value is: {}", value);
+    let optional_word = Some(String::from("rustlings"));
+    // TODO: Make this an if let statement whose value is "Some" type
+    word = optional_word {
+        println!("The word is: {}", word);
    } else {
-        println!("The optional value doesn't contain anything!");
+        println!("The optional word doesn't contain anything");
    }

-    let mut optional_values_vec: Vec<Option<i8>> = Vec::new();
+    let mut optional_integers_vec: Vec<Option<i8>> = Vec::new();
    for x in 1..10 {
-        optional_values_vec.push(Some(x));
+        optional_integers_vec.push(Some(x));
    }

-    // make this a while let statement - remember that vector.pop also adds another layer of Option<T>
+    // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
    // You can stack `Option<T>`'s into while let and if let
-    value = optional_values_vec.pop() {
-        println!("current value: {}", value);
+    integer = optional_integers_vec.pop() {
+        println!("current value: {}", integer);
    }
 }
--- a/exercises/primitive_types/README.md
+++ b/exercises/primitive_types/README.md
@@ -1,9 +1,9 @@
-### Primitive Types
+# Primitive Types

 Rust has a couple of basic types that are directly implemented into the
 compiler. In this section, we'll go through the most important ones.

-#### Book Sections
+## Further information

 - [Data Types](https://doc.rust-lang.org/stable/book/ch03-02-data-types.html)
 - [The Slice Type](https://doc.rust-lang.org/stable/book/ch04-03-slices.html)
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -1,5 +1,5 @@
 // primitive_types3.rs
-// Create an array with at least 100 elements in it where the ??? is. 
+// Create an array with at least 100 elements in it where the ??? is.
 // Execute `rustlings hint primitive_types3` for hints!

 // I AM NOT DONE
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -1,11 +1,16 @@
 // primitive_types6.rs
 // Use a tuple index to access the second element of `numbers`.
-// You can put this right into the `println!` where the ??? is.
+// You can put the expression for the second element where ??? is so that the test passes.
 // Execute `rustlings hint primitive_types6` for hints!

 // I AM NOT DONE

-fn main() {
+#[test]
+fn indexing_tuple() {
    let numbers = (1, 2, 3);
-    println!("The second number is {}", ???);
+    // Replace below ??? with the tuple indexing syntax.
+    let second = ???;
+
+    assert_eq!(2, second,
+        "This is not the 2nd number in the tuple!")
 }
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -1,5 +1,5 @@
-// test1.rs
-// This is a test for the following sections:
+// quiz1.rs
+// This is a quiz for the following sections:
 // - Variables
 // - Functions

--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -0,0 +1,30 @@
+// quiz2.rs
+// This is a quiz for the following sections:
+// - Strings
+
+// Ok, here are a bunch of values-- some are `String`s, some are `&str`s. Your
+// task is to call one of these two functions on each value depending on what
+// you think each value is. That is, add either `string_slice` or `string`
+// before the parentheses on each line. If you're right, it will compile!
+
+// I AM NOT DONE
+
+fn string_slice(arg: &str) {
+    println!("{}", arg);
+}
+fn string(arg: String) {
+    println!("{}", arg);
+}
+
+fn main() {
+    ???("blue");
+    ???("red".to_string());
+    ???(String::from("hi"));
+    ???("rust is fun!".to_owned());
+    ???("nice weather".into());
+    ???(format!("Interpolation {}", "Station"));
+    ???(&String::from("abc")[0..1]);
+    ???("  hello there ".trim());
+    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
+    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+}
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -1,8 +1,8 @@
-// test3.rs
-// This is a test for the following sections:
+// quiz3.rs
+// This is a quiz for the following sections:
 // - Tests

-// This test isn't testing our function -- make it do that in such a way that
+// This quiz isn't testing our function -- make it do that in such a way that
 // the test passes. Then write a second test that tests that we get the result
 // we expect to get when we call `times_two` with a negative number.
 // No hints, you can do this :)
@@ -24,6 +24,7 @@ mod tests {

    #[test]
    fn returns_twice_of_negative_numbers() {
-        // TODO write an assert for `times_two(-4)`
+        // TODO replace unimplemented!() with an assert for `times_two(-4)`
+        unimplemented!()
    }
 }
--- a/exercises/quiz4.rs
+++ b/exercises/quiz4.rs
@@ -1,9 +1,9 @@
-// test4.rs
-// This test covers the sections:
+// quiz4.rs
+// This quiz covers the sections:
 // - Modules
 // - Macros

-// Write a macro that passes the test! No hints this time, you can do it!
+// Write a macro that passes the quiz! No hints this time, you can do it!

 // I AM NOT DONE

--- a/exercises/standard_library_types/README.md
+++ b/exercises/standard_library_types/README.md
@@ -1,5 +1,10 @@
-For the Arc exercise check out the chapter [Shared-State Concurrency](https://doc.rust-lang.org/book/ch16-03-shared-state.html) of the Rust Book.
+# Standard library types

-For the Iterator exercise check out the chapters [Iterator](https://doc.rust-lang.org/book/ch13-02-iterators.html) of the Rust Book and the [Iterator documentation](https://doc.rust-lang.org/stable/std/iter/).
-Do not adjust your monitors-- iterators1.rs is indeed missing. Iterators is a challenging topic, so we're leaving space for a simpler exercise!
+This section will teach you about Box, Shared-State Concurrency and Iterators.

+## Further information
+
+- [Using Box to Point to Data on the Heap](https://doc.rust-lang.org/book/ch15-01-box.html)
+- [Shared-State Concurrency](https://doc.rust-lang.org/book/ch16-03-shared-state.html)
+- [Iterator](https://doc.rust-lang.org/book/ch13-02-iterators.html)
+- [Iterator documentation](https://doc.rust-lang.org/stable/std/iter/)
--- a/exercises/standard_library_types/arc1.rs
+++ b/exercises/standard_library_types/arc1.rs
@@ -1,11 +1,26 @@
 // arc1.rs
+// In this exercise, we are given a Vec of u32 called "numbers" with values ranging
+// from 0 to 99 -- [ 0, 1, 2, ..., 98, 99 ]
+// We would like to use this set of numbers within 8 different threads simultaneously.
+// Each thread is going to get the sum of every eighth value, with an offset.
+// The first thread (offset 0), will sum 0, 8, 16, ...
+// The second thread (offset 1), will sum 1, 9, 17, ...
+// The third thread (offset 2), will sum 2, 10, 18, ...
+// ...
+// The eighth thread (offset 7), will sum 7, 15, 23, ...
+
+// Because we are using threads, our values need to be thread-safe.  Therefore,
+// we are using Arc.  We need to make a change in each of the two TODOs.
+
+
 // Make this code compile by filling in a value for `shared_numbers` where the
-// TODO comment is and create an initial binding for `child_numbers`
-// somewhere. Try not to create any copies of the `numbers` Vec!
+// first TODO comment is, and create an initial binding for `child_numbers`
+// where the second TODO comment is. Try not to create any copies of the `numbers` Vec!
 // Execute `rustlings hint arc1` for hints :)

 // I AM NOT DONE

+#![forbid(unused_imports)] // Do not change this, (or the next) line.
 use std::sync::Arc;
 use std::thread;

@@ -15,12 +30,13 @@ fn main() {
    let mut joinhandles = Vec::new();

    for offset in 0..8 {
+        let child_numbers = // TODO
        joinhandles.push(thread::spawn(move || {
            let mut i = offset;
            let mut sum = 0;
            while i < child_numbers.len() {
                sum += child_numbers[i];
-                i += 5;
+                i += 8;
            }
            println!("Sum of offset {} is {}", offset, sum);
        }));
--- a/exercises/standard_library_types/box1.rs
+++ b/exercises/standard_library_types/box1.rs
@@ -0,0 +1,56 @@
+// box1.rs
+//
+// At compile time, Rust needs to know how much space a type takes up. This becomes problematic
+// for recursive types, where a value can have as part of itself another value of the same type.
+// To get around the issue, we can use a `Box` - a smart pointer used to store data on the heap,
+// which also allows us to wrap a recursive type.
+//
+// The recursive type we're implementing in this exercise is the `cons list` - a data structure
+// frequently found in functional programming languages. Each item in a cons list contains two
+// elements: the value of the current item and the next item. The last item is a value called `Nil`.
+//
+// Step 1: use a `Box` in the enum definition to make the code compile
+// Step 2: create both empty and non-empty cons lists by replacing `unimplemented!()`
+//
+// Note: the tests should not be changed
+//
+// Execute `rustlings hint box1` for hints :)
+
+// I AM NOT DONE
+
+#[derive(PartialEq, Debug)]
+pub enum List {
+    Cons(i32, List),
+    Nil,
+}
+
+fn main() {
+    println!("This is an empty cons list: {:?}", create_empty_list());
+    println!(
+        "This is a non-empty cons list: {:?}",
+        create_non_empty_list()
+    );
+}
+
+pub fn create_empty_list() -> List {
+    unimplemented!()
+}
+
+pub fn create_non_empty_list() -> List {
+    unimplemented!()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_create_empty_list() {
+        assert_eq!(List::Nil, create_empty_list())
+    }
+
+    #[test]
+    fn test_create_non_empty_list() {
+        assert_ne!(create_empty_list(), create_non_empty_list())
+    }
+}
--- a/exercises/standard_library_types/iterators1.rs
+++ b/exercises/standard_library_types/iterators1.rs
@@ -0,0 +1,24 @@
+// iterators1.rs
+// 
+//  Make me compile by filling in the `???`s
+//
+// When performing operations on elements within a collection, iterators are essential.
+// This module helps you get familiar with the structure of using an iterator and 
+// how to go through elements within an iterable collection.
+// 
+// Execute `rustlings hint iterators1` for hints :D
+
+// I AM NOT DONE
+
+fn main () {
+    let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
+
+    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
+
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
+    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
+    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2.1
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
+    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
+}
--- a/exercises/standard_library_types/iterators2.rs
+++ b/exercises/standard_library_types/iterators2.rs
@@ -1,26 +1,41 @@
 // iterators2.rs
-// In this module, you'll learn some of unique advantages that iterators can offer
-// Step 1. Complete the `capitalize_first` function to pass the first two cases
-// Step 2. Apply the `capitalize_first` function to a vector of strings, ensuring that it returns a vector of strings as well
-// Step 3. Apply the `capitalize_first` function again to a list, but try and ensure it returns a single string
+// In this exercise, you'll learn some of the unique advantages that iterators
+// can offer. Follow the steps to complete the exercise.
 // As always, there are hints if you execute `rustlings hint iterators2`!

 // I AM NOT DONE

+// Step 1.
+// Complete the `capitalize_first` function.
+// "hello" -> "Hello"
 pub fn capitalize_first(input: &str) -> String {
    let mut c = input.chars();
    match c.next() {
        None => String::new(),
-        Some(first) => first.collect::<String>() + c.as_str(),
+        Some(first) => ???,
    }
 }

+// Step 2.
+// Apply the `capitalize_first` function to a slice of string slices.
+// Return a vector of strings.
+// ["hello", "world"] -> ["Hello", "World"]
+pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
+    vec![]
+}
+
+// Step 3.
+// Apply the `capitalize_first` function again to a slice of string slices.
+// Return a single string.
+// ["hello", " ", "world"] -> "Hello World"
+pub fn capitalize_words_string(words: &[&str]) -> String {
+    String::new()
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;

-    // Step 1.
-    // Tests that verify your `capitalize_first` function implementation
    #[test]
    fn test_success() {
        assert_eq!(capitalize_first("hello"), "Hello");
@@ -31,18 +46,15 @@ mod tests {
        assert_eq!(capitalize_first(""), "");
    }

-    // Step 2.
    #[test]
    fn test_iterate_string_vec() {
        let words = vec!["hello", "world"];
-        let capitalized_words: Vec<String> = // TODO
-        assert_eq!(capitalized_words, ["Hello", "World"]);
+        assert_eq!(capitalize_words_vector(&words), ["Hello", "World"]);
    }

    #[test]
    fn test_iterate_into_string() {
        let words = vec!["hello", " ", "world"];
-        let capitalized_words = // TODO
-        assert_eq!(capitalized_words, "Hello World");
+        assert_eq!(capitalize_words_string(&words), "Hello World");
    }
 }
--- a/exercises/standard_library_types/iterators3.rs
+++ b/exercises/standard_library_types/iterators3.rs
@@ -1,11 +1,10 @@
 // iterators3.rs
 // This is a bigger exercise than most of the others! You can do it!
 // Here is your mission, should you choose to accept it:
-// 1. Complete the divide function to get the first four tests to pass
-// 2. Uncomment the last two tests and get them to pass by filling in
-//    values for `x` using `division_results`.
+// 1. Complete the divide function to get the first four tests to pass.
+// 2. Get the remaining tests to pass by completing the result_with_list and
+//    list_of_results functions.
 // Execute `rustlings hint iterators3` to get some hints!
-// Have fun :-)

 // I AM NOT DONE

@@ -21,16 +20,28 @@ pub struct NotDivisibleError {
    divisor: i32,
 }

-// This function should calculate `a` divided by `b` if `a` is
-// evenly divisible by b.
-// Otherwise, it should return a suitable error.
+// Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
+// Otherwise, return a suitable error.
 pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {}

+// Complete the function and return a value of the correct type so the test passes.
+// Desired output: Ok([1, 11, 1426, 3])
+fn result_with_list() -> () {
+    let numbers = vec![27, 297, 38502, 81];
+    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+}
+
+// Complete the function and return a value of the correct type so the test passes.
+// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
+fn list_of_results() -> () {
+    let numbers = vec![27, 297, 38502, 81];
+    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;

-    // Tests that verify your `divide` function implementation
    #[test]
    fn test_success() {
        assert_eq!(divide(81, 9), Ok(9));
@@ -57,22 +68,16 @@ mod tests {
        assert_eq!(divide(0, 81), Ok(0));
    }

-    // Iterator exercises using your `divide` function
-    /*
    #[test]
-    fn result_with_list() {
-        let numbers = vec![27, 297, 38502, 81];
-        let division_results = numbers.into_iter().map(|n| divide(n, 27));
-        let x //... Fill in here!
-        assert_eq!(format!("{:?}", x), "Ok([1, 11, 1426, 3])");
+    fn test_result_with_list() {
+        assert_eq!(format!("{:?}", result_with_list()), "Ok([1, 11, 1426, 3])");
    }

    #[test]
-    fn list_of_results() {
-        let numbers = vec![27, 297, 38502, 81];
-        let division_results = numbers.into_iter().map(|n| divide(n, 27));
-        let x //... Fill in here!
-        assert_eq!(format!("{:?}", x), "[Ok(1), Ok(11), Ok(1426), Ok(3)]");
+    fn test_list_of_results() {
+        assert_eq!(
+            format!("{:?}", list_of_results()),
+            "[Ok(1), Ok(11), Ok(1426), Ok(3)]"
+        );
    }
-    */
 }
--- a/exercises/standard_library_types/iterators4.rs
+++ b/exercises/standard_library_types/iterators4.rs
@@ -3,13 +3,13 @@
 // I AM NOT DONE

 pub fn factorial(num: u64) -> u64 {
-    // Complete this function to return factorial of num
+    // Complete this function to return the factorial of num
    // Do not use:
    // - return
-    // For extra fun don't use:
+    // Try not to use:
    // - imperative style loops (for, while)
    // - additional variables
-    // For the most fun don't use:
+    // For an extra challenge, don't use:
    // - recursion
    // Execute `rustlings hint iterators4` for hints.
 }
--- a/exercises/standard_library_types/iterators5.rs
+++ b/exercises/standard_library_types/iterators5.rs
@@ -0,0 +1,124 @@
+// iterators5.rs
+
+// Let's define a simple model to track Rustlings exercise progress. Progress
+// will be modelled using a hash map. The name of the exercise is the key and
+// the progress is the value. Two counting functions were created to count the
+// number of exercises with a given progress. These counting functions use
+// imperative style for loops. Recreate this counting functionality using
+// iterators. Only the two iterator methods (count_iterator and
+// count_collection_iterator) need to be modified.
+// Execute `rustlings hint
+// iterators5` for hints.
+//
+// Make the code compile and the tests pass.
+
+// I AM NOT DONE
+
+use std::collections::HashMap;
+
+#[derive(PartialEq, Eq)]
+enum Progress {
+    None,
+    Some,
+    Complete,
+}
+
+fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
+    let mut count = 0;
+    for val in map.values() {
+        if val == &value {
+            count += 1;
+        }
+    }
+    count
+}
+
+fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
+    // map is a hashmap with String keys and Progress values.
+    // map = { "variables1": Complete, "from_str": None, ... }
+}
+
+fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
+    let mut count = 0;
+    for map in collection {
+        for val in map.values() {
+            if val == &value {
+                count += 1;
+            }
+        }
+    }
+    count
+}
+
+fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
+    // collection is a slice of hashmaps.
+    // collection = [{ "variables1": Complete, "from_str": None, ... },
+    //     { "variables2": Complete, ... }, ... ]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn count_complete() {
+        let map = get_map();
+        assert_eq!(3, count_iterator(&map, Progress::Complete));
+    }
+
+    #[test]
+    fn count_equals_for() {
+        let map = get_map();
+        assert_eq!(
+            count_for(&map, Progress::Complete),
+            count_iterator(&map, Progress::Complete)
+        );
+    }
+
+    #[test]
+    fn count_collection_complete() {
+        let collection = get_vec_map();
+        assert_eq!(
+            6,
+            count_collection_iterator(&collection, Progress::Complete)
+        );
+    }
+
+    #[test]
+    fn count_collection_equals_for() {
+        let collection = get_vec_map();
+        assert_eq!(
+            count_collection_for(&collection, Progress::Complete),
+            count_collection_iterator(&collection, Progress::Complete)
+        );
+    }
+
+    fn get_map() -> HashMap<String, Progress> {
+        use Progress::*;
+
+        let mut map = HashMap::new();
+        map.insert(String::from("variables1"), Complete);
+        map.insert(String::from("functions1"), Complete);
+        map.insert(String::from("hashmap1"), Complete);
+        map.insert(String::from("arc1"), Some);
+        map.insert(String::from("as_ref_mut"), None);
+        map.insert(String::from("from_str"), None);
+
+        map
+    }
+
+    fn get_vec_map() -> Vec<HashMap<String, Progress>> {
+        use Progress::*;
+
+        let map = get_map();
+
+        let mut other = HashMap::new();
+        other.insert(String::from("variables2"), Complete);
+        other.insert(String::from("functions2"), Complete);
+        other.insert(String::from("if1"), Complete);
+        other.insert(String::from("from_into"), None);
+        other.insert(String::from("try_from_into"), None);
+
+        vec![map, other]
+    }
+}
--- a/exercises/strings/README.md
+++ b/exercises/strings/README.md
@@ -1,9 +1,9 @@
-### Strings
+# Strings

 Rust has two string types, a string slice (`&str`) and an owned string (`String`).
 We're not going to dictate when you should use which one, but we'll show you how
 to identify and create them, as well as use them.

-#### Book Sections
+## Further information

 - [Strings](https://doc.rust-lang.org/book/ch08-02-strings.html)
--- a/exercises/structs/README.md
+++ b/exercises/structs/README.md
@@ -1,7 +1,8 @@
-### Structs
+# Structs

-Rust has three struct types: a classic c struct, a tuple struct, and a unit struct.
+Rust has three struct types: a classic C struct, a tuple struct, and a unit struct.

-#### Book Sections
+## Further information

- [Structures](https://doc.rust-lang.org/rust-by-example/custom_types/structs.html)
+- [Structures](https://doc.rust-lang.org/book/ch05-01-defining-structs.html)
+- [Method Syntax](https://doc.rust-lang.org/book/ch05-03-method-syntax.html)
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -1,6 +1,5 @@
 // structs2.rs
 // Address all the TODOs to make the tests pass!
-// No hints, just do it!

 // I AM NOT DONE

--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -0,0 +1,82 @@
+// structs3.rs
+// Structs contain data, but can also have logic. In this exercise we have
+// defined the Package struct and we want to test some logic attached to it.
+// Make the code compile and the tests pass!
+// If you have issues execute `rustlings hint structs3`
+
+// I AM NOT DONE
+
+#[derive(Debug)]
+struct Package {
+    sender_country: String,
+    recipient_country: String,
+    weight_in_grams: i32,
+}
+
+impl Package {
+    fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
+        if weight_in_grams <= 0 {
+            // Something goes here...
+        } else {
+            return Package {
+                sender_country,
+                recipient_country,
+                weight_in_grams,
+            };
+        }
+    }
+
+    fn is_international(&self) -> ??? {
+        // Something goes here...
+    }
+
+    fn get_fees(&self, cents_per_gram: i32) -> ??? {
+        // Something goes here... 
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    #[should_panic]
+    fn fail_creating_weightless_package() {
+        let sender_country = String::from("Spain");
+        let recipient_country = String::from("Austria");
+
+        Package::new(sender_country, recipient_country, -2210);
+    }
+
+    #[test]
+    fn create_international_package() {
+        let sender_country = String::from("Spain");
+        let recipient_country = String::from("Russia");
+
+        let package = Package::new(sender_country, recipient_country, 1200);
+
+        assert!(package.is_international());
+    }
+
+    #[test]
+    fn create_local_package() {
+        let sender_country = String::from("Canada");
+        let recipient_country = sender_country.clone();
+
+        let package = Package::new(sender_country, recipient_country, 1200);
+
+        assert!(!package.is_international());
+    }
+
+    #[test]
+    fn calculate_transport_fees() {
+        let sender_country = String::from("Spain");
+        let recipient_country = String::from("Spain");
+
+        let cents_per_gram = ???;
+
+        let package = Package::new(sender_country, recipient_country, 1500);
+
+        assert_eq!(package.get_fees(cents_per_gram), 4500);
+    }
+}
--- a/exercises/test2.rs
+++ b/exercises/test2.rs
@@ -1,30 +0,0 @@
-// test2.rs
-// This is a test for the following sections:
-// - Strings
-
-// Ok, here are a bunch of values-- some are `Strings`, some are `&strs`. Your
-// task is to call one of these two functions on each value depending on what
-// you think each value is. That is, add either `string_slice` or `string`
-// before the parentheses on each line. If you're right, it will compile!
-
-// I AM NOT DONE
-
-fn string_slice(arg: &str) {
-    println!("{}", arg);
-}
-fn string(arg: String) {
-    println!("{}", arg);
-}
-
-fn main() {
-    ("blue");
-    ("red".to_string());
-    (String::from("hi"));
-    ("rust is fun!".to_owned());
-    ("nice weather".into());
-    (format!("Interpolation {}", "Station"));
-    (&String::from("abc")[0..1]);
-    ("  hello there ".trim());
-    ("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ("mY sHiFt KeY iS sTiCkY".to_lowercase());
-}
--- a/exercises/tests/README.md
+++ b/exercises/tests/README.md
@@ -1,7 +1,7 @@
-### Tests
+# Tests

 Going out of order from the book to cover tests -- many of the following exercises will ask you to make tests pass!

-#### Book Sections
+## Further information

 - [Writing Tests](https://doc.rust-lang.org/book/ch11-01-writing-tests.html)
--- a/exercises/tests/tests3.rs
+++ b/exercises/tests/tests3.rs
@@ -18,4 +18,9 @@ mod tests {
    fn is_true_when_even() {
        assert!();
    }
+
+    #[test]
+    fn is_false_when_odd() {
+        assert!();
+    }
 }
--- a/exercises/threads/README.md
+++ b/exercises/threads/README.md
@@ -1 +1,9 @@
-For this exercise check out the [Dining Philosophers example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html) and the chapter [Concurrency](https://doc.rust-lang.org/book/ch16-01-threads.html) of the Rust Book.
+# Threads
+
+In most current operating systems, an executed program’s code is run in a process, and the operating system manages multiple processes at once.
+Within your program, you can also have independent parts that run simultaneously. The features that run these independent parts are called threads.
+
+## Further information
+
+- [Dining Philosophers example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html)
+- [Using Threads to Run Code Simultaneously](https://doc.rust-lang.org/book/ch16-01-threads.html)
--- a/exercises/threads/threads1.rs
+++ b/exercises/threads/threads1.rs
@@ -1,7 +1,8 @@
 // threads1.rs
 // Make this compile! Execute `rustlings hint threads1` for hints :)
-// The idea is the thread spawned on line 21 is completing jobs while the main thread is
-// monitoring progress until 10 jobs are completed. If you see 6 lines
+// The idea is the thread spawned on line 22 is completing jobs while the main thread is
+// monitoring progress until 10 jobs are completed. Because of the difference between the
+// spawned threads' sleep time, and the waiting threads sleep time, when you see 6 lines
 // of "waiting..." and the program ends without timing out when running,
 // you've got it :)

--- a/exercises/traits/README.md
+++ b/exercises/traits/README.md
@@ -0,0 +1,19 @@
+# Traits
+
+A trait is a collection of methods.
+
+Data types can implement traits. To do so, the methods making up the trait are defined for the data type. For example, the `String` data type implements the `From<&str>` trait. This allows a user to write `String::from("hello")`.
+
+In this way, traits are somewhat similar to Java interfaces and C++ abstract classes.
+
+Some additional common Rust traits include:
+- `Clone` (the `clone` method)
+- `Display` (which allows formatted display via `{}`)
+- `Debug` (which allows formatted display via `{:?}`)
+
+Because traits indicate shared behavior between data types, they are useful when writing generics.
+
+
+## Further information
+
+- [Traits](https://doc.rust-lang.org/book/ch10-02-traits.html)
--- a/exercises/traits/traits1.rs
+++ b/exercises/traits/traits1.rs
@@ -1,21 +1,21 @@
 // traits1.rs
 // Time to implement some traits!
-// 
+//
 // Your task is to implement the trait
 // `AppendBar' for the type `String'.
-// 
+//
 // The trait AppendBar has only one function,
 // which appends "Bar" to any object
 // implementing this trait.

 // I AM NOT DONE
+
 trait AppendBar {
    fn append_bar(self) -> Self;
 }

 impl AppendBar for String {
    //Add your code here
-
 }

 fn main() {
@@ -40,5 +40,4 @@ mod tests {
            String::from("BarBar")
        );
    }
-
-}
+}
--- a/exercises/traits/traits2.rs
+++ b/exercises/traits/traits2.rs
@@ -1,12 +1,12 @@
 // traits2.rs
-// 
+//
 // Your task is to implement the trait
 // `AppendBar' for a vector of strings.
-// 
+//
 // To implement this trait, consider for
 // a moment what it means to 'append "Bar"'
 // to a vector of strings.
-// 
+//
 // No boiler plate code this time,
 // you can do this!

@@ -18,9 +18,6 @@ trait AppendBar {

 //TODO: Add your code here

-
-
-
 #[cfg(test)]
 mod tests {
    use super::*;
@@ -31,5 +28,4 @@ mod tests {
        assert_eq!(foo.pop().unwrap(), String::from("Bar"));
        assert_eq!(foo.pop().unwrap(), String::from("Foo"));
    }
-
 }
--- a/exercises/variables/README.md
+++ b/exercises/variables/README.md
@@ -1,7 +1,9 @@
-### Variables
+# Variables

-Here you'll learn about simple variables.
+In Rust, variables are immutable by default.
+When a variable is immutable, once a value is bound to a name, you can’t change that value.
+You can make them mutable by adding mut in front of the variable name.

-#### Book Sections
+## Further information

 - [Variables and Mutability](https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html)
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -6,6 +6,6 @@
 fn main() {
    let x = 3;
    println!("Number {}", x);
-    x = 5;
+    x = 5; // don't change this line
    println!("Number {}", x);
 }
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -4,8 +4,8 @@
 // I AM NOT DONE

 fn main() {
-    let number = "3";
-    println!("Number {}", number);
+    let number = "T-H-R-E-E";
+    println!("Spell a Number : {}", number);
    number = 3;
-    println!("Number {}", number);
+    println!("Number plus two is : {}", number + 2);
 }
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -0,0 +1,9 @@
+// variables6.rs
+// Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
+
+// I AM NOT DONE
+
+const NUMBER = 3;
+fn main() {
+    println!("Number {}", NUMBER);
+}
--- a/info.toml
+++ b/info.toml
@@ -52,24 +52,24 @@ because we want to assign a different typed value to an existing variable. Somet
 you may also like to reuse existing variable names because you are just converting
 values to different types like in this exercise.
 Fortunately Rust has a powerful solution to this problem: 'Shadowing'!
-You can read more about 'Shadowing' in the book's section 'Variables and Mutability'.
+You can read more about 'Shadowing' in the book's section 'Variables and Mutability':
+https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#shadowing
 Try to solve this exercise afterwards using this technique."""

-# IF
-
 [[exercises]]
-name = "if1"
-path = "exercises/if/if1.rs"
-mode = "test"
+name = "variables6"
+path = "exercises/variables/variables6.rs"
+mode = "compile"
 hint = """
-It's possible to do this in one line if you would like!
-Some similar examples from other languages:
- In C(++) this would be: `a > b ? a : b`
- In Python this would be:  `a if a > b else b`
-Remember in Rust that:
- the `if` condition does not need to be surrounded by parentheses
- `if`/`else` conditionals are expressions
- Each condition is followed by a `{}` block."""
+We know about variables and mutability, but there is another important type of
+variable available; constants.
+Constants are always immutable and they are declared with keyword 'const' rather
+than keyword 'let'.
+Constants types must also always be annotated.
+
+Read more about constants under 'Differences Between Variables and Constants' in the book's section 'Variables and Mutability':
+https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#differences-between-variables-and-constants
+"""

 # FUNCTIONS

@@ -121,254 +121,36 @@ They are not the same. There are two solutions:
 1. Add a `return` ahead of `num * num;`
 2. remove `;`, make it to be `num * num`"""

+# IF
+
+[[exercises]]
+name = "if1"
+path = "exercises/if/if1.rs"
+mode = "test"
+hint = """
+It's possible to do this in one line if you would like!
+Some similar examples from other languages:
+- In C(++) this would be: `a > b ? a : b`
+- In Python this would be:  `a if a > b else b`
+Remember in Rust that:
+- the `if` condition does not need to be surrounded by parentheses
+- `if`/`else` conditionals are expressions
+- Each condition is followed by a `{}` block."""
+
+[[exercises]]
+name = "if2"
+path = "exercises/if/if2.rs"
+mode = "test"
+hint = """
+For that first compiler error, it's important in Rust that each conditional
+block return the same type! To get the tests passing, you will need a couple
+conditions checking different input values."""
+
 # TEST 1

 [[exercises]]
-name = "test1"
-path = "exercises/test1.rs"
-mode = "test"
-hint = "No hints this time ;)"
-
-# PRIMITIVE TYPES
-
-[[exercises]]
-name = "primitive_types1"
-path = "exercises/primitive_types/primitive_types1.rs"
-mode = "compile"
-hint = "No hints this time ;)"
-
-[[exercises]]
-name = "primitive_types2"
-path = "exercises/primitive_types/primitive_types2.rs"
-mode = "compile"
-hint = "No hints this time ;)"
-
-[[exercises]]
-name = "primitive_types3"
-path = "exercises/primitive_types/primitive_types3.rs"
-mode = "compile"
-hint = """
-There's a shorthand to initialize Arrays with a certain size that does not
-require you to type in 100 items (but you certainly can if you want!).
-For example, you can do:
-let array = ["Are we there yet?"; 10];
-
-Bonus: what are some other things you could have that would return true
-for `a.len() >= 100`?"""
-
-[[exercises]]
-name = "primitive_types4"
-path = "exercises/primitive_types/primitive_types4.rs"
-mode = "test"
-hint = """
-Take a look at the Understanding Ownership -> Slices -> Other Slices section of the book:
-https://doc.rust-lang.org/book/ch04-03-slices.html
-and use the starting and ending indices of the items in the Array
-that you want to end up in the slice.
-
-If you're curious why the first argument of `assert_eq!` does not
-have an ampersand for a reference since the second argument is a
-reference, take a look at the Deref coercions section of the book:
-https://doc.rust-lang.org/book/ch15-02-deref.html"""
-
-[[exercises]]
-name = "primitive_types5"
-path = "exercises/primitive_types/primitive_types5.rs"
-mode = "compile"
-hint = """
-Take a look at the Data Types -> The Tuple Type section of the book:
-https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
-Particularly the part about destructuring (second to last example in the section).
-You'll need to make a pattern to bind `name` and `age` to the appropriate parts
-of the tuple. You can do it!!"""
-
-[[exercises]]
-name = "primitive_types6"
-path = "exercises/primitive_types/primitive_types6.rs"
-mode = "compile"
-hint = """
-While you could use a destructuring `let` for the tuple here, try
-indexing into it instead, as explained in the last example of the
-Data Types -> The Tuple Type section of the book:
-https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
-Now you have another tool in your toolbox!"""
-
-# STRUCTS
-
-[[exercises]]
-name = "structs1"
-path = "exercises/structs/structs1.rs"
-mode = "test"
-hint = "No hints this time ;)"
-
-[[exercises]]
-name = "structs2"
-path = "exercises/structs/structs2.rs"
-mode = "test"
-hint = "No hints this time ;)"
-
-# STRINGS
-
-[[exercises]]
-name = "strings1"
-path = "exercises/strings/strings1.rs"
-mode = "compile"
-hint = """
-The `current_favorite_color` function is currently returning a string slice with the `'static`
-lifetime. We know this because the data of the string lives in our code itself -- it doesn't
-come from a file or user input or another program -- so it will live as long as our program
-lives. But it is still a string slice. There's one way to create a `String` by converting a
-string slice covered in the Strings chapter of the book, and another way that uses the `From`
-trait."""
-
-[[exercises]]
-name = "strings2"
-path = "exercises/strings/strings2.rs"
-mode = "compile"
-hint = """
-Yes, it would be really easy to fix this by just changing the value bound to `word` to be a
-string slice instead of a `String`, wouldn't it?? There is a way to add one character to line
-9, though, that will coerce the `String` into a string slice."""
-
-# TEST 2
-
-[[exercises]]
-name = "test2"
-path = "exercises/test2.rs"
-mode = "compile"
-hint = "No hints this time ;)"
-
-# ENUMS
-
-[[exercises]]
-name = "enums1"
-path = "exercises/enums/enums1.rs"
-mode = "compile"
-hint = """
-Hint: The declaration of the enumeration type has not been defined yet."""
-
-[[exercises]]
-name = "enums2"
-path = "exercises/enums/enums2.rs"
-mode = "compile"
-hint = """
-Hint: you can create enumerations that have different variants with different types
-such as no data, anonymous structs, a single string, tuples, ...etc"""
-
-[[exercises]]
-name = "enums3"
-path = "exercises/enums/enums3.rs"
-mode = "test"
-hint = "No hints this time ;)"
-
-# TESTS
-
-[[exercises]]
-name = "tests1"
-path = "exercises/tests/tests1.rs"
-mode = "test"
-hint = """
-You don't even need to write any code to test -- you can just test values and run that, even
-though you wouldn't do that in real life :) `assert!` is a macro that needs an argument.
-Depending on the value of the argument, `assert!` will do nothing (in which case the test will
-pass) or `assert!` will panic (in which case the test will fail). So try giving different values
-to `assert!` and see which ones compile, which ones pass, and which ones fail :)"""
-
-[[exercises]]
-name = "tests2"
-path = "exercises/tests/tests2.rs"
-mode = "test"
-hint = """
-Like the previous exercise, you don't need to write any code to get this test to compile and
-run. `assert_eq!` is a macro that takes two arguments and compares them. Try giving it two
-values that are equal! Try giving it two arguments that are different! Try giving it two values
-that are of different types! Try switching which argument comes first and which comes second!"""
-
-[[exercises]]
-name = "tests3"
-path = "exercises/tests/tests3.rs"
-mode = "test"
-hint = """
-You can call a function right where you're passing arguments to `assert!` -- so you could do
-something like `assert!(having_fun())`. If you want to check that you indeed get false, you
-can negate the result of what you're doing using `!`, like `assert!(!having_fun())`."""
-
-# TEST 3
-
-[[exercises]]
-name = "test3"
-path = "exercises/test3.rs"
-mode = "test"
-hint = "No hints this time ;)"
-
-# MODULES
-
-[[exercises]]
-name = "modules1"
-path = "exercises/modules/modules1.rs"
-mode = "compile"
-hint = """
-Everything is private in Rust by default-- but there's a keyword we can use
-to make something public! The compiler error should point to the thing that
-needs to be public."""
-
-[[exercises]]
-name = "modules2"
-path = "exercises/modules/modules2.rs"
-mode = "compile"
-hint = """
-The delicious_snacks module is trying to present an external
-interface (the `fruit` and `veggie` constants) that is different than
-its internal structure (the `fruits` and `veggies` modules and
-associated constants). It's almost there except for one keyword missing for
-each constant."""
-
-# MACROS
-
-[[exercises]]
-name = "macros1"
-path = "exercises/macros/macros1.rs"
-mode = "compile"
-hint = """
-When you call a macro, you need to add something special compared to a
-regular function call. If you're stuck, take a look at what's inside
-`my_macro`."""
-
-[[exercises]]
-name = "macros2"
-path = "exercises/macros/macros2.rs"
-mode = "compile"
-hint = """
-Macros don't quite play by the same rules as the rest of Rust, in terms of
-what's available where.
-
-Unlike other things in Rust, the order of "where you define a macro" versus
-"where you use it" actually matters."""
-
-[[exercises]]
-name = "macros3"
-path = "exercises/macros/macros3.rs"
-mode = "compile"
-hint = """
-In order to use a macro outside of its module, you need to do something
-special to the module to lift the macro out into its parent.
-
-The same trick also works on "extern crate" statements for crates that have
-exported macros, if you've seen any of those around."""
-
-[[exercises]]
-name = "macros4"
-path = "exercises/macros/macros4.rs"
-mode = "compile"
-hint = """
-You only need to add a single character to make this compile.
-The way macros are written, it wants to see something between each
-"macro arm", so it can separate them."""
-# TEST 4
-
-[[exercises]]
-name = "test4"
-path = "exercises/test4.rs"
+name = "quiz1"
+path = "exercises/quiz1.rs"
 mode = "test"
 hint = "No hints this time ;)"

@@ -428,6 +210,229 @@ So the end goal is to:
   - since we're not creating a new vec in `main` anymore, we need to create
     a new vec in `fill_vec`, similarly to the way we did in `main`"""

+# PRIMITIVE TYPES
+
+[[exercises]]
+name = "primitive_types1"
+path = "exercises/primitive_types/primitive_types1.rs"
+mode = "compile"
+hint = "No hints this time ;)"
+
+[[exercises]]
+name = "primitive_types2"
+path = "exercises/primitive_types/primitive_types2.rs"
+mode = "compile"
+hint = "No hints this time ;)"
+
+[[exercises]]
+name = "primitive_types3"
+path = "exercises/primitive_types/primitive_types3.rs"
+mode = "compile"
+hint = """
+There's a shorthand to initialize Arrays with a certain size that does not
+require you to type in 100 items (but you certainly can if you want!).
+For example, you can do:
+let array = ["Are we there yet?"; 10];
+
+Bonus: what are some other things you could have that would return true
+for `a.len() >= 100`?"""
+
+[[exercises]]
+name = "primitive_types4"
+path = "exercises/primitive_types/primitive_types4.rs"
+mode = "test"
+hint = """
+Take a look at the Understanding Ownership -> Slices -> Other Slices section of the book:
+https://doc.rust-lang.org/book/ch04-03-slices.html
+and use the starting and ending indices of the items in the Array
+that you want to end up in the slice.
+
+If you're curious why the first argument of `assert_eq!` does not
+have an ampersand for a reference since the second argument is a
+reference, take a look at the Deref coercions section of the book:
+https://doc.rust-lang.org/book/ch15-02-deref.html"""
+
+[[exercises]]
+name = "primitive_types5"
+path = "exercises/primitive_types/primitive_types5.rs"
+mode = "compile"
+hint = """
+Take a look at the Data Types -> The Tuple Type section of the book:
+https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
+Particularly the part about destructuring (second to last example in the section).
+You'll need to make a pattern to bind `name` and `age` to the appropriate parts
+of the tuple. You can do it!!"""
+
+[[exercises]]
+name = "primitive_types6"
+path = "exercises/primitive_types/primitive_types6.rs"
+mode = "test"
+hint = """
+While you could use a destructuring `let` for the tuple here, try
+indexing into it instead, as explained in the last example of the
+Data Types -> The Tuple Type section of the book:
+https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
+Now you have another tool in your toolbox!"""
+
+# STRUCTS
+
+[[exercises]]
+name = "structs1"
+path = "exercises/structs/structs1.rs"
+mode = "test"
+hint = """
+Rust has more than one type of struct. Three actually, all variants are used to package related data together.
+There are normal (or classic) structs. These are named collections of related data stored in fields.
+Tuple structs are basically just named tuples.
+Finally, Unit structs. These don't have any fields and are useful for generics.
+
+In this exercise you need to complete and implement one of each kind.
+Read more about structs in The Book: https://doc.rust-lang.org/book/ch05-01-defining-structs.html"""
+
+[[exercises]]
+name = "structs2"
+path = "exercises/structs/structs2.rs"
+mode = "test"
+hint = """
+Creating instances of structs is easy, all you need to do is assign some values to its fields.
+There are however some shortcuts that can be taken when instantiating structs.
+Have a look in The Book, to find out more: https://doc.rust-lang.org/stable/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax"""
+
+[[exercises]]
+name = "structs3"
+path = "exercises/structs/structs3.rs"
+mode = "test"
+hint = """
+The new method needs to panic if the weight is physically impossible :), how do we do that in Rust?
+
+For is_international: What makes a package international? Seems related to the places it goes through right?
+
+For calculate_transport_fees: Bigger is more expensive usually, we don't have size, but something may fit the bill here :)
+
+Have a look in The Book, to find out more about method implementations: https://doc.rust-lang.org/book/ch05-03-method-syntax.html"""
+
+# ENUMS
+
+[[exercises]]
+name = "enums1"
+path = "exercises/enums/enums1.rs"
+mode = "compile"
+hint = """
+Hint: The declaration of the enumeration type has not been defined yet."""
+
+[[exercises]]
+name = "enums2"
+path = "exercises/enums/enums2.rs"
+mode = "compile"
+hint = """
+Hint: you can create enumerations that have different variants with different types
+such as no data, anonymous structs, a single string, tuples, ...etc"""
+
+[[exercises]]
+name = "enums3"
+path = "exercises/enums/enums3.rs"
+mode = "test"
+hint = "No hints this time ;)"
+
+# MODULES
+
+[[exercises]]
+name = "modules1"
+path = "exercises/modules/modules1.rs"
+mode = "compile"
+hint = """
+Everything is private in Rust by default-- but there's a keyword we can use
+to make something public! The compiler error should point to the thing that
+needs to be public."""
+
+[[exercises]]
+name = "modules2"
+path = "exercises/modules/modules2.rs"
+mode = "compile"
+hint = """
+The delicious_snacks module is trying to present an external
+interface (the `fruit` and `veggie` constants) that is different than
+its internal structure (the `fruits` and `veggies` modules and
+associated constants). It's almost there except for one keyword missing for
+each constant."""
+
+# COLLECTIONS
+
+[[exercises]]
+name = "vec1"
+path = "exercises/collections/vec1.rs"
+mode = "test"
+hint = """
+In Rust, there are two ways to define a Vector.
+1. One way is to use the `Vec::new()` function to create a new vector
+  and fill it with the `push()` method.
+2. The second way, which is simpler is to use the `vec![]` macro and
+  define your elements inside the square brackets.
+Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
+of the Rust book to learn more.
+"""
+
+[[exercises]]
+name = "vec2"
+path = "exercises/collections/vec2.rs"
+mode = "test"
+hint = """
+Hint 1: `i` is each element from the Vec as they are being iterated.
+  Can you try multiplying this?
+Hint 2: Check the suggestion from the compiler error ;)
+"""
+
+[[exercises]]
+name = "hashmap1"
+path = "exercises/collections/hashmap1.rs"
+mode = "test"
+hint = """
+Hint 1: Take a look at the return type of the function to figure out
+  the type for the `basket`.
+Hint 2: Number of fruits should be at least 5. And you have to put
+  at least three different types of fruits.
+"""
+
+[[exercises]]
+name = "hashmap2"
+path = "exercises/collections/hashmap2.rs"
+mode = "test"
+hint = """
+Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
+Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
+"""
+
+# STRINGS
+
+[[exercises]]
+name = "strings1"
+path = "exercises/strings/strings1.rs"
+mode = "compile"
+hint = """
+The `current_favorite_color` function is currently returning a string slice with the `'static`
+lifetime. We know this because the data of the string lives in our code itself -- it doesn't
+come from a file or user input or another program -- so it will live as long as our program
+lives. But it is still a string slice. There's one way to create a `String` by converting a
+string slice covered in the Strings chapter of the book, and another way that uses the `From`
+trait."""
+
+[[exercises]]
+name = "strings2"
+path = "exercises/strings/strings2.rs"
+mode = "compile"
+hint = """
+Yes, it would be really easy to fix this by just changing the value bound to `word` to be a
+string slice instead of a `String`, wouldn't it?? There is a way to add one character to line
+9, though, that will coerce the `String` into a string slice."""
+
+# TEST 2
+
+[[exercises]]
+name = "quiz2"
+path = "exercises/quiz2.rs"
+mode = "compile"
+hint = "No hints this time ;)"
+
 # ERROR HANDLING

 [[exercises]]
@@ -465,7 +470,7 @@ and give it a try!"""
 [[exercises]]
 name = "errors3"
 path = "exercises/error_handling/errors3.rs"
-mode = "test"
+mode = "compile"
 hint = """
 If other functions can return a `Result`, why shouldn't `main`?"""

@@ -476,7 +481,7 @@ mode = "test"
 hint = """
 First hint: To figure out what type should go where the ??? is, take a look
 at the test helper function `test_with_str`, since it returns whatever
-`read_and_validate` returns and`test_with_str` has its signature fully
+`read_and_validate` returns and `test_with_str` has its signature fully
 specified.


@@ -507,6 +512,40 @@ get a warning if you don't handle a `Result` that you get in your
 function. Read more about that in the `std::result` module docs:
 https://doc.rust-lang.org/std/result/#results-must-be-used"""

+# Generics
+
+[[exercises]]
+name = "generics1"
+path = "exercises/generics/generics1.rs"
+mode = "compile"
+hint = """
+Vectors in rust make use of generics to create dynamically sized arrays of any type.
+You need to tell the compiler what type we are pushing onto this vector."""
+
+[[exercises]]
+name = "generics2"
+path = "exercises/generics/generics2.rs"
+mode = "test"
+hint = """
+Currently we are wrapping only values of type 'u32'.
+Maybe we could update the explicit references to this data type somehow?
+
+If you are still stuck https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions
+"""
+
+[[exercises]]
+name = "generics3"
+path = "exercises/generics/generics3.rs"
+mode = "test"
+hint = """
+To find the best solution to this challenge you're going to need to think back to your
+knowledge of traits, specifically Trait Bound Syntax -  you may also need this: "use std::fmt::Display;"
+
+This is definitely harder than the last two exercises! You need to think about not only making the
+ReportCard struct generic, but also the correct property - you will need to change the implementation
+of the struct slightly too...you can do it!
+"""
+
 # OPTIONS / RESULTS

 [[exercises]]
@@ -514,13 +553,15 @@ name = "option1"
 path = "exercises/option/option1.rs"
 mode = "compile"
 hint = """
-Check out some functions of Option:
+Hint 1: Check out some functions of Option:
 is_some
 is_none
 unwrap

 and:
 pattern matching
+
+Hint 2: There are no sensible defaults for the value of an Array; the values need to be filled before use.
 """

 [[exercises]]
@@ -534,8 +575,7 @@ https://doc.rust-lang.org/rust-by-example/flow_control/while_let.html

 Remember that Options can be stacked in if let and while let.
 For example: Some(Some(variable)) = variable2
-
-
+Also see Option::flatten
 """

 [[exercises]]
@@ -547,79 +587,6 @@ hint = """
 It should be doing some checking, returning an `Err` result if those checks fail, and only
 returning an `Ok` result if those checks determine that everything is... okay :)"""

-#  CLIPPY
-
-[[exercises]]
-name = "clippy1"
-path = "exercises/clippy/clippy1.rs"
-mode = "clippy"
-hint = """
-Floating point calculations are usually imprecise, so asking if two values are exactly equal is asking for trouble"""
-
-[[exercises]]
-name = "clippy2"
-path = "exercises/clippy/clippy2.rs"
-mode = "clippy"
-hint = """
-`for` loops over Option values are more clearly expressed as an `if let`"""
-
-# STANDARD LIBRARY TYPES
-
-[[exercises]]
-name = "arc1"
-path = "exercises/standard_library_types/arc1.rs"
-mode = "compile"
-hint = """
-Make `shared_numbers` be an `Arc` from the numbers vector. Then, in order
-to avoid creating a copy of `numbers`, you'll need to create `child_numbers`
-inside the loop but still in the main thread.
-
-`child_numbers` should be a clone of the Arc of the numbers instead of a
-thread-local copy of the numbers."""
-
-[[exercises]]
-name = "iterators2"
-path = "exercises/standard_library_types/iterators2.rs"
-mode = "test"
-hint = """
-Step 1
-You need to call something on `first` before it can be collected
-Currently its type is `char`. Have a look at the methods that are available on that type:
-https://doc.rust-lang.org/std/primitive.char.html
-
-
-Step 2
-First you'll need to turn the Vec into an iterator
-Then you'll need to apply your function unto each item in the vector
-P.s. Don't forget to collect() at the end!
-
-
-Step 3.
-This is very similar to the previous test. The only real change is that you will need to
-alter the type that collect is coerced into. For a bonus you could try doing this with a
-turbofish"""
-
-[[exercises]]
-name = "iterators3"
-path = "exercises/standard_library_types/iterators3.rs"
-mode = "test"
-hint = """
-Minor hint: In each of the two cases in the match in main, you can create x with either
-a 'turbofish' or by hinting the type of x to the compiler. You may try both.
-
-Major hint: Have a look at the Iter trait and at the explanation of its collect function.
-Especially the part about Result is interesting."""
-
-[[exercises]]
-name = "iterators4"
-path = "exercises/standard_library_types/iterators4.rs"
-mode = "test"
-hint = """
-In an imperative language you might write a for loop to iterate through
-multiply the values into a mutable variable. Or you might write code more
-functionally with recursion and a match clause. But you can also use ranges
-and iterators to solve this in rust."""
-
 # TRAITS

 [[exercises]]
@@ -636,43 +603,167 @@ name = "traits2"
 path = "exercises/traits/traits2.rs"
 mode = "test"
 hint = """
-Notice how the trait takes ownership of 'self',and returns `Self'. 
+Notice how the trait takes ownership of 'self',and returns `Self'.
 Try mutating the incoming string vector.

-Vectors provide suitable methods for adding an element at the end. See 
+Vectors provide suitable methods for adding an element at the end. See
 the documentation at: https://doc.rust-lang.org/std/vec/struct.Vec.html"""

-# Generics
+# TESTS

 [[exercises]]
-name = "generics1"
-path = "exercises/generics/generics1.rs"
+name = "tests1"
+path = "exercises/tests/tests1.rs"
+mode = "test"
+hint = """
+You don't even need to write any code to test -- you can just test values and run that, even
+though you wouldn't do that in real life :) `assert!` is a macro that needs an argument.
+Depending on the value of the argument, `assert!` will do nothing (in which case the test will
+pass) or `assert!` will panic (in which case the test will fail). So try giving different values
+to `assert!` and see which ones compile, which ones pass, and which ones fail :)"""
+
+[[exercises]]
+name = "tests2"
+path = "exercises/tests/tests2.rs"
+mode = "test"
+hint = """
+Like the previous exercise, you don't need to write any code to get this test to compile and
+run. `assert_eq!` is a macro that takes two arguments and compares them. Try giving it two
+values that are equal! Try giving it two arguments that are different! Try giving it two values
+that are of different types! Try switching which argument comes first and which comes second!"""
+
+[[exercises]]
+name = "tests3"
+path = "exercises/tests/tests3.rs"
+mode = "test"
+hint = """
+You can call a function right where you're passing arguments to `assert!` -- so you could do
+something like `assert!(having_fun())`. If you want to check that you indeed get false, you
+can negate the result of what you're doing using `!`, like `assert!(!having_fun())`."""
+
+# TEST 3
+
+[[exercises]]
+name = "quiz3"
+path = "exercises/quiz3.rs"
+mode = "test"
+hint = "No hints this time ;)"
+
+# STANDARD LIBRARY TYPES
+
+[[exercises]]
+name = "box1"
+path = "exercises/standard_library_types/box1.rs"
+mode = "test"
+hint = """
+Step 1
+The compiler's message should help: since we cannot store the value of the actual type
+when working with recursive types, we need to store a reference (pointer) to its value.
+We should, therefore, place our `List` inside a `Box`. More details in the book here:
+https://doc.rust-lang.org/book/ch15-01-box.html#enabling-recursive-types-with-boxes
+
+Step 2
+Creating an empty list should be fairly straightforward (hint: peek at the assertions).
+For a non-empty list keep in mind that we want to use our Cons "list builder".
+Although the current list is one of integers (i32), feel free to change the definition
+and try other types!
+"""
+
+[[exercises]]
+name = "arc1"
+path = "exercises/standard_library_types/arc1.rs"
 mode = "compile"
 hint = """
-Vectors in rust make use of generics to create dynamically sized arrays of any type.
-You need to tell the compiler what type we are pushing onto this vector."""
+Make `shared_numbers` be an `Arc` from the numbers vector. Then, in order
+to avoid creating a copy of `numbers`, you'll need to create `child_numbers`
+inside the loop but still in the main thread.

-[[exercises]]
-name = "generics2"
-path = "exercises/generics/generics2.rs"
-mode = "test"
-hint = """
-Think carefully about what we need to do here. Currently we are wrapping only values of
-type 'u32'. Maybe we need to update the explicit references to this data type somehow?
+`child_numbers` should be a clone of the Arc of the numbers instead of a
+thread-local copy of the numbers.
+
+This is a simple exercise if you understand the underlying concepts, but if this
+is too much of a struggle, consider reading through all of Chapter 16 in the book:
+https://doc.rust-lang.org/stable/book/ch16-00-concurrency.html
 """

 [[exercises]]
-name = "generics3"
-path = "exercises/generics/generics3.rs"
+name = "iterators1"
+path = "exercises/standard_library_types/iterators1.rs"
+mode = "compile"
+hint = """
+Step 1:
+We need to apply something to the collection `my_fav_fruits` before we start to go through
+it. What could that be? Take a look at the struct definition for a vector for inspiration:
+https://doc.rust-lang.org/std/vec/struct.Vec.html.
+Step 2 & step 2.1:
+Very similar to the lines above and below. You've got this!
+Step 3:
+An iterator goes through all elements in a collection, but what if we've run out of
+elements? What should we expect here? If you're stuck, take a look at
+https://doc.rust-lang.org/std/iter/trait.Iterator.html for some ideas.
+"""
+
+[[exercises]]
+name = "iterators2"
+path = "exercises/standard_library_types/iterators2.rs"
 mode = "test"
 hint = """
-To find the best solution to this challenge you're going to need to think back to your 
-knowledge of traits, specifically Trait Bound Syntax -  you may also need this: "use std::fmt::Display;"
+Step 1
+The variable `first` is a `char`. It needs to be capitalized and added to the
+remaining characters in `c` in order to return the correct `String`.
+The remaining characters in `c` can be viewed as a string slice using the
+`as_str` method.
+The documentation for `char` contains many useful methods.
+https://doc.rust-lang.org/std/primitive.char.html

-This is definitely harder than the last two exercises! You need to think about not only making the
-ReportCard struct generic, but also the correct property - you will need to change the implementation
-of the struct slightly too...you can do it!
-"""
+Step 2
+Create an iterator from the slice. Transform the iterated values by applying
+the `capitalize_first` function. Remember to collect the iterator.
+
+Step 3.
+This is surprising similar to the previous solution. Collect is very powerful
+and very general. Rust just needs to know the desired type."""
+
+[[exercises]]
+name = "iterators3"
+path = "exercises/standard_library_types/iterators3.rs"
+mode = "test"
+hint = """
+The divide function needs to return the correct error when even division is not
+possible.
+
+The division_results variable needs to be collected into a collection type.
+
+The result_with_list function needs to return a single Result where the success
+case is a vector of integers and the failure case is a DivisionError.
+
+The list_of_results function needs to return a vector of results."""
+
+[[exercises]]
+name = "iterators4"
+path = "exercises/standard_library_types/iterators4.rs"
+mode = "test"
+hint = """
+In an imperative language, you might write a for loop that updates
+a mutable variable. Or, you might write code utilizing recursion
+and a match clause. In Rust you can take another functional
+approach, computing the factorial elegantly with ranges and iterators."""
+
+[[exercises]]
+name = "iterators5"
+path = "exercises/standard_library_types/iterators5.rs"
+mode = "test"
+hint = """
+The documentation for the std::iter::Iterator trait contains numerous methods
+that would be helpful here.
+
+Return 0 from count_collection_iterator to make the code compile in order to
+test count_iterator.
+
+The collection variable in count_collection_iterator is a slice of HashMaps. It
+needs to be converted into an iterator in order to use the iterator methods.
+
+The fold method can be useful in the count_collection_iterator function."""

 # THREADS

@@ -713,12 +804,78 @@ If you've learned from the sample solutions, I encourage you to come
 back to this exercise and try it again in a few days to reinforce
 what you've learned :)"""

+# MACROS
+
+[[exercises]]
+name = "macros1"
+path = "exercises/macros/macros1.rs"
+mode = "compile"
+hint = """
+When you call a macro, you need to add something special compared to a
+regular function call. If you're stuck, take a look at what's inside
+`my_macro`."""
+
+[[exercises]]
+name = "macros2"
+path = "exercises/macros/macros2.rs"
+mode = "compile"
+hint = """
+Macros don't quite play by the same rules as the rest of Rust, in terms of
+what's available where.
+
+Unlike other things in Rust, the order of "where you define a macro" versus
+"where you use it" actually matters."""
+
+[[exercises]]
+name = "macros3"
+path = "exercises/macros/macros3.rs"
+mode = "compile"
+hint = """
+In order to use a macro outside of its module, you need to do something
+special to the module to lift the macro out into its parent.
+
+The same trick also works on "extern crate" statements for crates that have
+exported macros, if you've seen any of those around."""
+
+[[exercises]]
+name = "macros4"
+path = "exercises/macros/macros4.rs"
+mode = "compile"
+hint = """
+You only need to add a single character to make this compile.
+The way macros are written, it wants to see something between each
+"macro arm", so it can separate them."""
+
+# TEST 4
+
+[[exercises]]
+name = "quiz4"
+path = "exercises/quiz4.rs"
+mode = "test"
+hint = "No hints this time ;)"
+
+#  CLIPPY
+
+[[exercises]]
+name = "clippy1"
+path = "exercises/clippy/clippy1.rs"
+mode = "clippy"
+hint = """
+Floating point calculations are usually imprecise, so asking if two values are exactly equal is asking for trouble"""
+
+[[exercises]]
+name = "clippy2"
+path = "exercises/clippy/clippy2.rs"
+mode = "clippy"
+hint = """
+`for` loops over Option values are more clearly expressed as an `if let`"""
+
 # TYPE CONVERSIONS

 [[exercises]]
 name = "using_as"
 path = "exercises/conversions/using_as.rs"
-mode = "compile"
+mode = "test"
 hint = """
 Use the `as` operator to cast one of the operands in the last line of the
 `average` function into the expected return type."""
@@ -735,7 +892,7 @@ name = "try_from_into"
 path = "exercises/conversions/try_from_into.rs"
 mode = "test"
 hint = """
-Follow the steps provided right before the `From` implementation.
+Follow the steps provided right before the `TryFrom` implementation.
 You can also use the example at https://doc.rust-lang.org/std/convert/trait.TryFrom.html"""

 [[exercises]]
@@ -750,5 +907,6 @@ name = "from_str"
 path = "exercises/conversions/from_str.rs"
 mode = "test"
 hint = """
-If you've already solved try_from_into.rs, then this is almost a copy-paste.
-Otherwise, go ahead and solve try_from_into.rs first."""
+The implementation of FromStr should return an Ok with a Person object,
+or an Err with an error if the string is not valid.
+This is almost like the `try_from_into` exercise."""
--- a/install.ps1
+++ b/install.ps1
@@ -35,7 +35,7 @@ if (Get-Command cargo -ErrorAction SilentlyContinue) {
 function vercomp($v1, $v2) {
    if ($v1 -eq $v2) {
       return 0
-    } 
+    }

    $v1 = $v1.Replace(".", "0")
    $v2 = $v2.Replace(".", "0")
@@ -53,7 +53,7 @@ function vercomp($v1, $v2) {
 }

 $rustVersion = $(rustc --version).Split(" ")[1]
-$minRustVersion = "1.31"
+$minRustVersion = "1.39"
 if ((vercomp $rustVersion $minRustVersion) -eq 2) {
    Write-Host "WARNING: Rust version is too old: $rustVersion - needs at least $minRustVersion"
    Write-Host "Please update Rust with 'rustup update'"
--- a/install.sh
+++ b/install.sh
@@ -30,6 +30,22 @@ else
    exit 1
 fi

+# Look up python installations, starting with 3 with a fallback of 2
+if [ -x "$(command -v python3)" ]
+then
+    PY="$(command -v python3)"
+elif [ -x "$(command -v python)" ]
+then
+    PY="$(command -v python)"
+elif [ -x "$(command -v python2)" ]
+then
+    PY="$(command -v python2)"
+else
+    echo "ERROR: No working python installation was found"
+    echo "Please install python and add it to the PATH variable"
+    exit 1
+fi
+
 # Function that compares two versions strings v1 and v2 given in arguments (e.g 1.31 and 1.33.0).
 # Returns 1 if v1 > v2, 0 if v1 == v2, 2 if v1 < v2.
 function vercomp() {
@@ -71,7 +87,7 @@ function vercomp() {
 }

 RustVersion=$(rustc --version | cut -d " " -f 2)
-MinRustVersion=1.31
+MinRustVersion=1.39
 vercomp $RustVersion $MinRustVersion
 if [ $? -eq 2 ]
 then
@@ -86,12 +102,30 @@ Path=${1:-rustlings/}
 echo "Cloning Rustlings at $Path..."
 git clone -q https://github.com/rust-lang/rustlings $Path

-Version=$(curl -s https://api.github.com/repos/rust-lang/rustlings/releases/latest | python -c "import json,sys;obj=json.load(sys.stdin);print(obj['tag_name']);")
+cd $Path
+
+Version=$(curl -s https://api.github.com/repos/rust-lang/rustlings/releases/latest | ${PY} -c "import json,sys;obj=json.load(sys.stdin);print(obj['tag_name']);")
 CargoBin="${CARGO_HOME:-$HOME/.cargo}/bin"

+if [[ -z ${Version} ]]
+then
+    echo "The latest tag version could not be fetched remotely."
+    echo "Using the local git repository..."
+    Version=$(ls -tr .git/refs/tags/ | tail -1)
+    if [[ -z ${Version}  ]]
+    then
+        echo "No valid tag version found"
+        echo "Rustlings will be installed using the main branch"
+        Version="main"
+    else
+        Version="tags/${Version}"
+    fi
+else
+    Version="tags/${Version}"
+fi
+
 echo "Checking out version $Version..."
-cd $Path
-git checkout -q tags/$Version
+git checkout -q ${Version}

 echo "Installing the 'rustlings' executable..."
 cargo install --force --path .
--- a/src/exercise.rs
+++ b/src/exercise.rs
@@ -1,5 +1,6 @@
 use regex::Regex;
 use serde::Deserialize;
+use std::env;
 use std::fmt::{self, Display, Formatter};
 use std::fs::{self, remove_file, File};
 use std::io::Read;
@@ -11,15 +12,26 @@ const I_AM_DONE_REGEX: &str = r"(?m)^\s*///?\s*I\s+AM\s+NOT\s+DONE";
 const CONTEXT: usize = 2;
 const CLIPPY_CARGO_TOML_PATH: &str = "./exercises/clippy/Cargo.toml";

+// Get a temporary file name that is hopefully unique
+#[inline]
 fn temp_file() -> String {
-    format!("./temp_{}", process::id())
+    let thread_id: String = format!("{:?}", std::thread::current().id())
+        .chars()
+        .filter(|c| c.is_alphanumeric())
+        .collect();
+
+    format!("./temp_{}_{}", process::id(), thread_id)
 }

-#[derive(Deserialize, Copy, Clone)]
+// The mode of the exercise.
+#[derive(Deserialize, Copy, Clone, Debug)]
 #[serde(rename_all = "lowercase")]
 pub enum Mode {
+    // Indicates that the exercise should be compiled as a binary
    Compile,
+    // Indicates that the exercise should be compiled as a test harness
    Test,
+    // Indicates that the exercise should be linted with clippy
    Clippy,
 }

@@ -28,41 +40,60 @@ pub struct ExerciseList {
    pub exercises: Vec<Exercise>,
 }

-#[derive(Deserialize)]
+// A representation of a rustlings exercise.
+// This is deserialized from the accompanying info.toml file
+#[derive(Deserialize, Debug)]
 pub struct Exercise {
+    // Name of the exercise
    pub name: String,
+    // The path to the file containing the exercise's source code
    pub path: PathBuf,
+    // The mode of the exercise (Test, Compile, or Clippy)
    pub mode: Mode,
+    // The hint text associated with the exercise
    pub hint: String,
 }

+// An enum to track of the state of an Exercise.
+// An Exercise can be either Done or Pending
 #[derive(PartialEq, Debug)]
 pub enum State {
+    // The state of the exercise once it's been completed
    Done,
+    // The state of the exercise while it's not completed yet
    Pending(Vec<ContextLine>),
 }

+// The context information of a pending exercise
 #[derive(PartialEq, Debug)]
 pub struct ContextLine {
+    // The source code that is still pending completion
    pub line: String,
+    // The line number of the source code still pending completion
    pub number: usize,
+    // Whether or not this is important
    pub important: bool,
 }

+// The result of compiling an exercise
 pub struct CompiledExercise<'a> {
    exercise: &'a Exercise,
    _handle: FileHandle,
 }

 impl<'a> CompiledExercise<'a> {
+    // Run the compiled exercise
    pub fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
        self.exercise.run()
    }
 }

+// A representation of an already executed binary
 #[derive(Debug)]
 pub struct ExerciseOutput {
+    // The textual contents of the standard output of the binary
    pub stdout: String,
+    // The textual contents of the standard error of the binary
    pub stderr: String,
 }

@@ -96,8 +127,12 @@ name = "{}"
 path = "{}.rs""#,
                    self.name, self.name, self.name
                );
-                fs::write(CLIPPY_CARGO_TOML_PATH, cargo_toml)
-                    .expect("Failed to write 📎 Clippy 📎 Cargo.toml file.");
+                let cargo_toml_error_msg = if env::var("NO_EMOJI").is_ok() {
+                    "Failed to write Clippy Cargo.toml file."
+                } else {
+                    "Failed to write 📎 Clippy 📎 Cargo.toml file."
+                };
+                fs::write(CLIPPY_CARGO_TOML_PATH, cargo_toml).expect(cargo_toml_error_msg);
                // To support the ability to run the clipy exercises, build
                // an executable, in addition to running clippy. With a
                // compilation failure, this would silently fail. But we expect
@@ -109,7 +144,7 @@ path = "{}.rs""#,
                    .expect("Failed to compile!");
                // Due to an issue with Clippy, a cargo clean is required to catch all lints.
                // See https://github.com/rust-lang/rust-clippy/issues/2604
-                // This is already fixed on master branch. See this issue to track merging into Cargo:
+                // This is already fixed on Clippy's master branch. See this issue to track merging into Cargo:
                // https://github.com/rust-lang/rust-clippy/issues/3837
                Command::new("cargo")
                    .args(&["clean", "--manifest-path", CLIPPY_CARGO_TOML_PATH])
@@ -140,7 +175,12 @@ path = "{}.rs""#,
    }

    fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
+        let arg = match self.mode {
+            Mode::Test => "--show-output",
+            _ => "",
+        };
        let cmd = Command::new(&temp_file())
+            .arg(arg)
            .output()
            .expect("Failed to run 'run' command");

@@ -197,6 +237,16 @@ path = "{}.rs""#,

        State::Pending(context)
    }
+
+    // Check that the exercise looks to be solved using self.state()
+    // This is not the best way to check since
+    // the user can just remove the "I AM NOT DONE" string from the file
+    // without actually having solved anything.
+    // The only other way to truly check this would to compile and run
+    // the exercise; which would be both costly and counterintuitive
+    pub fn looks_done(&self) -> bool {
+        self.state() == State::Done
+    }
 }

 impl Display for Exercise {
@@ -205,6 +255,7 @@ impl Display for Exercise {
    }
 }

+#[inline]
 fn clean() {
    let _ignored = remove_file(&temp_file());
 }
@@ -280,4 +331,16 @@ mod test {

        assert_eq!(exercise.state(), State::Done);
    }
+
+    #[test]
+    fn test_exercise_with_output() {
+        let exercise = Exercise {
+            name: "exercise_with_output".into(),
+            path: PathBuf::from("tests/fixture/success/testSuccess.rs"),
+            mode: Mode::Test,
+            hint: String::new(),
+        };
+        let out = exercise.compile().unwrap().run().unwrap();
+        assert!(out.stdout.contains("THIS TEST TOO SHALL PASS"));
+    }
 }
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,13 +1,13 @@
 use crate::exercise::{Exercise, ExerciseList};
 use crate::run::run;
 use crate::verify::verify;
-use clap::{crate_version, App, Arg, SubCommand};
+use argh::FromArgs;
 use console::Emoji;
 use notify::DebouncedEvent;
 use notify::{RecommendedWatcher, RecursiveMode, Watcher};
 use std::ffi::OsStr;
 use std::fs;
-use std::io;
+use std::io::{self, prelude::*};
 use std::path::Path;
 use std::process::{Command, Stdio};
 use std::sync::mpsc::channel;
@@ -22,28 +22,91 @@ mod exercise;
 mod run;
 mod verify;

-fn main() {
-    let matches = App::new("rustlings")
-        .version(crate_version!())
-        .author("Olivia Hugger, Carol Nichols")
-        .about("Rustlings is a collection of small exercises to get you used to writing and reading Rust code")
-        .subcommand(SubCommand::with_name("verify").alias("v").about("Verifies all exercises according to the recommended order"))
-        .subcommand(SubCommand::with_name("watch").alias("w").about("Reruns `verify` when files were edited"))
-        .subcommand(
-            SubCommand::with_name("run")
-                .alias("r")
-                .about("Runs/Tests a single exercise")
-                .arg(Arg::with_name("name").required(true).index(1)),
-        )
-        .subcommand(
-            SubCommand::with_name("hint")
-                .alias("h")
-                .about("Returns a hint for the current exercise")
-                .arg(Arg::with_name("name").required(true).index(1)),
-        )
-        .get_matches();
+// In sync with crate version
+const VERSION: &str = "4.4.0";

-    if None == matches.subcommand_name() {
+#[derive(FromArgs, PartialEq, Debug)]
+/// Rustlings is a collection of small exercises to get you used to writing and reading Rust code
+struct Args {
+    /// show outputs from the test exercises
+    #[argh(switch)]
+    nocapture: bool,
+    /// show the executable version
+    #[argh(switch, short = 'v')]
+    version: bool,
+    #[argh(subcommand)]
+    nested: Option<Subcommands>,
+}
+
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand)]
+enum Subcommands {
+    Verify(VerifyArgs),
+    Watch(WatchArgs),
+    Run(RunArgs),
+    Hint(HintArgs),
+    List(ListArgs),
+}
+
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand, name = "verify")]
+/// Verifies all exercises according to the recommended order
+struct VerifyArgs {}
+
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand, name = "watch")]
+/// Reruns `verify` when files were edited
+struct WatchArgs {}
+
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand, name = "run")]
+/// Runs/Tests a single exercise
+struct RunArgs {
+    #[argh(positional)]
+    /// the name of the exercise
+    name: String,
+}
+
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand, name = "hint")]
+/// Returns a hint for the given exercise
+struct HintArgs {
+    #[argh(positional)]
+    /// the name of the exercise
+    name: String,
+}
+
+#[derive(FromArgs, PartialEq, Debug)]
+#[argh(subcommand, name = "list")]
+/// Lists the exercises available in Rustlings
+struct ListArgs {
+    #[argh(switch, short = 'p')]
+    /// show only the paths of the exercises
+    paths: bool,
+    #[argh(switch, short = 'n')]
+    /// show only the names of the exercises
+    names: bool,
+    #[argh(option, short = 'f')]
+    /// provide a string to match exercise names
+    /// comma separated patterns are acceptable
+    filter: Option<String>,
+    #[argh(switch, short = 'u')]
+    /// display only exercises not yet solved
+    unsolved: bool,
+    #[argh(switch, short = 's')]
+    /// display only exercises that have been solved
+    solved: bool,
+}
+
+fn main() {
+    let args: Args = argh::from_env();
+
+    if args.version {
+        println!("v{}", VERSION);
+        std::process::exit(0);
+    }
+
+    if args.nested.is_none() {
        println!();
        println!(r#"       welcome to...                      "#);
        println!(r#"                 _   _ _                  "#);
@@ -73,73 +136,146 @@ fn main() {

    let toml_str = &fs::read_to_string("info.toml").unwrap();
    let exercises = toml::from_str::<ExerciseList>(toml_str).unwrap().exercises;
+    let verbose = args.nocapture;

-    if let Some(ref matches) = matches.subcommand_matches("run") {
-        let name = matches.value_of("name").unwrap();
-
-        let matching_exercise = |e: &&Exercise| name == e.name;
-
-        let exercise = exercises.iter().find(matching_exercise).unwrap_or_else(|| {
-            println!("No exercise found for your given name!");
-            std::process::exit(1)
-        });
-
-        run(&exercise).unwrap_or_else(|_| std::process::exit(1));
-    }
-
-    if let Some(ref matches) = matches.subcommand_matches("hint") {
-        let name = matches.value_of("name").unwrap();
-
-        let exercise = exercises
-            .iter()
-            .find(|e| name == e.name)
-            .unwrap_or_else(|| {
-                println!("No exercise found for your given name!");
-                std::process::exit(1)
+    let command = args.nested.unwrap_or_else(|| {
+        let text = fs::read_to_string("default_out.txt").unwrap();
+        println!("{}", text);
+        std::process::exit(0);
+    });
+    match command {
+        Subcommands::List(subargs) => {
+            if !subargs.paths && !subargs.names {
+                println!("{:<17}\t{:<46}\t{:<7}", "Name", "Path", "Status");
+            }
+            let mut exercises_done: u16 = 0;
+            let filters = subargs.filter.clone().unwrap_or_default().to_lowercase();
+            exercises.iter().for_each(|e| {
+                let fname = format!("{}", e.path.display());
+                let filter_cond = filters
+                    .split(',')
+                    .filter(|f| !f.trim().is_empty())
+                    .any(|f| e.name.contains(&f) || fname.contains(&f));
+                let status = if e.looks_done() {
+                    exercises_done += 1;
+                    "Done"
+                } else {
+                    "Pending"
+                };
+                let solve_cond = {
+                    (e.looks_done() && subargs.solved)
+                        || (!e.looks_done() && subargs.unsolved)
+                        || (!subargs.solved && !subargs.unsolved)
+                };
+                if solve_cond && (filter_cond || subargs.filter.is_none()) {
+                    let line = if subargs.paths {
+                        format!("{}\n", fname)
+                    } else if subargs.names {
+                        format!("{}\n", e.name)
+                    } else {
+                        format!("{:<17}\t{:<46}\t{:<7}\n", e.name, fname, status)
+                    };
+                    // Somehow using println! leads to the binary panicking
+                    // when its output is piped.
+                    // So, we're handling a Broken Pipe error and exiting with 0 anyway
+                    let stdout = std::io::stdout();
+                    {
+                        let mut handle = stdout.lock();
+                        handle.write_all(line.as_bytes()).unwrap_or_else(|e| {
+                            match e.kind() {
+                                std::io::ErrorKind::BrokenPipe => std::process::exit(0),
+                                _ => std::process::exit(1),
+                            };
+                        });
+                    }
+                }
            });
+            let percentage_progress = exercises_done as f32 / exercises.len() as f32 * 100.0;
+            println!(
+                "Progress: You completed {} / {} exercises ({:.2} %).",
+                exercises_done,
+                exercises.len(),
+                percentage_progress
+            );
+            std::process::exit(0);
+        }

-        println!("{}", exercise.hint);
-    }
+        Subcommands::Run(subargs) => {
+            let exercise = find_exercise(&subargs.name, &exercises);

-    if matches.subcommand_matches("verify").is_some() {
-        verify(&exercises).unwrap_or_else(|_| std::process::exit(1));
-    }
+            run(&exercise, verbose).unwrap_or_else(|_| std::process::exit(1));
+        }

-    if matches.subcommand_matches("watch").is_some() {
-        if watch(&exercises).is_ok() {
+        Subcommands::Hint(subargs) => {
+            let exercise = find_exercise(&subargs.name, &exercises);
+
+            println!("{}", exercise.hint);
+        }
+
+        Subcommands::Verify(_subargs) => {
+            verify(&exercises, verbose).unwrap_or_else(|_| std::process::exit(1));
+        }
+
+        Subcommands::Watch(_subargs) => {
+            if let Err(e) = watch(&exercises, verbose) {
+                println!(
+                    "Error: Could not watch your progress. Error message was {:?}.",
+                    e
+                );
+                println!("Most likely you've run out of disk space or your 'inotify limit' has been reached.");
+                std::process::exit(1);
+            }
            println!(
                "{emoji} All exercises completed! {emoji}",
                emoji = Emoji("🎉", "★")
            );
-            println!("");
+            println!();
+            println!("+----------------------------------------------------+");
+            println!("|          You made it to the Fe-nish line!          |");
+            println!("+--------------------------  ------------------------+");
+            println!("                          \\/                         ");
+            println!("     ▒▒          ▒▒▒▒▒▒▒▒      ▒▒▒▒▒▒▒▒          ▒▒   ");
+            println!("   ▒▒▒▒  ▒▒    ▒▒        ▒▒  ▒▒        ▒▒    ▒▒  ▒▒▒▒ ");
+            println!("   ▒▒▒▒  ▒▒  ▒▒            ▒▒            ▒▒  ▒▒  ▒▒▒▒ ");
+            println!(" ░░▒▒▒▒░░▒▒  ▒▒            ▒▒            ▒▒  ▒▒░░▒▒▒▒ ");
+            println!("   ▓▓▓▓▓▓▓▓  ▓▓      ▓▓██  ▓▓  ▓▓██      ▓▓  ▓▓▓▓▓▓▓▓ ");
+            println!("     ▒▒▒▒    ▒▒      ████  ▒▒  ████      ▒▒░░  ▒▒▒▒   ");
+            println!("       ▒▒  ▒▒▒▒▒▒        ▒▒▒▒▒▒        ▒▒▒▒▒▒  ▒▒     ");
+            println!("         ▒▒▒▒▒▒▒▒▒▒▓▓▓▓▓▓▒▒▒▒▒▒▒▒▓▓▒▒▓▓▒▒▒▒▒▒▒▒       ");
+            println!("           ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒         ");
+            println!("             ▒▒▒▒▒▒▒▒▒▒██▒▒▒▒▒▒██▒▒▒▒▒▒▒▒▒▒           ");
+            println!("           ▒▒  ▒▒▒▒▒▒▒▒▒▒██████▒▒▒▒▒▒▒▒▒▒  ▒▒         ");
+            println!("         ▒▒    ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒    ▒▒       ");
+            println!("       ▒▒    ▒▒    ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒    ▒▒    ▒▒     ");
+            println!("       ▒▒  ▒▒    ▒▒                  ▒▒    ▒▒  ▒▒     ");
+            println!("           ▒▒  ▒▒                      ▒▒  ▒▒         ");
+            println!();
            println!("We hope you enjoyed learning about the various aspects of Rust!");
            println!(
                "If you noticed any issues, please don't hesitate to report them to our repo."
            );
            println!("You can also contribute your own exercises to help the greater community!");
-            println!("");
+            println!();
            println!("Before reporting an issue or contributing, please read our guidelines:");
-            println!("https://github.com/rust-lang/rustlings/blob/master/CONTRIBUTING.md");
+            println!("https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md");
        }
    }
-
-    if matches.subcommand_name().is_none() {
-        let text = fs::read_to_string("default_out.txt").unwrap();
-        println!("{}", text);
-    }
 }

 fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>) {
    let failed_exercise_hint = Arc::clone(failed_exercise_hint);
-    println!("Type 'hint' to get help");
+    println!("Type 'hint' or open the corresponding README.md file to get help or type 'clear' to clear the screen.");
    thread::spawn(move || loop {
        let mut input = String::new();
        match io::stdin().read_line(&mut input) {
            Ok(_) => {
-                if input.trim().eq("hint") {
+                let input = input.trim();
+                if input.eq("hint") {
                    if let Some(hint) = &*failed_exercise_hint.lock().unwrap() {
                        println!("{}", hint);
                    }
+                } else if input.eq("clear") {
+                    println!("\x1B[2J\x1B[1;1H");
                } else {
                    println!("unknown command: {}", input);
                }
@@ -149,7 +285,17 @@ fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>) {
    });
 }

-fn watch(exercises: &[Exercise]) -> notify::Result<()> {
+fn find_exercise<'a>(name: &str, exercises: &'a [Exercise]) -> &'a Exercise {
+    exercises
+        .iter()
+        .find(|e| e.name == name)
+        .unwrap_or_else(|| {
+            println!("No exercise found for '{}'!", name);
+            std::process::exit(1)
+        })
+}
+
+fn watch(exercises: &[Exercise], verbose: bool) -> notify::Result<()> {
    /* Clears the terminal with an ANSI escape code.
    Works in UNIX and newer Windows terminals. */
    fn clear_screen() {
@@ -164,7 +310,7 @@ fn watch(exercises: &[Exercise]) -> notify::Result<()> {
    clear_screen();

    let to_owned_hint = |t: &Exercise| t.hint.to_owned();
-    let failed_exercise_hint = match verify(exercises.iter()) {
+    let failed_exercise_hint = match verify(exercises.iter(), verbose) {
        Ok(_) => return Ok(()),
        Err(exercise) => Arc::new(Mutex::new(Some(to_owned_hint(exercise)))),
    };
@@ -177,9 +323,15 @@ fn watch(exercises: &[Exercise]) -> notify::Result<()> {
                        let filepath = b.as_path().canonicalize().unwrap();
                        let pending_exercises = exercises
                            .iter()
-                            .skip_while(|e| !filepath.ends_with(&e.path));
+                            .skip_while(|e| !filepath.ends_with(&e.path))
+                            // .filter(|e| filepath.ends_with(&e.path))
+                            .chain(
+                                exercises
+                                    .iter()
+                                    .filter(|e| !e.looks_done() && !filepath.ends_with(&e.path)),
+                            );
                        clear_screen();
-                        match verify(pending_exercises) {
+                        match verify(pending_exercises, verbose) {
                            Ok(_) => return Ok(()),
                            Err(exercise) => {
                                let mut failed_exercise_hint = failed_exercise_hint.lock().unwrap();
--- a/src/run.rs
+++ b/src/run.rs
@@ -2,15 +2,22 @@ use crate::exercise::{Exercise, Mode};
 use crate::verify::test;
 use indicatif::ProgressBar;

-pub fn run(exercise: &Exercise) -> Result<(), ()> {
+// Invoke the rust compiler on the path of the given exercise,
+// and run the ensuing binary.
+// The verbose argument helps determine whether or not to show
+// the output from the test harnesses (if the mode of the exercise is test)
+pub fn run(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
    match exercise.mode {
-        Mode::Test => test(exercise)?,
+        Mode::Test => test(exercise, verbose)?,
        Mode::Compile => compile_and_run(exercise)?,
        Mode::Clippy => compile_and_run(exercise)?,
    }
    Ok(())
 }

+// Invoke the rust compiler on the path of the given exercise
+// and run the ensuing binary.
+// This is strictly for non-test binaries, so output is displayed
 fn compile_and_run(exercise: &Exercise) -> Result<(), ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -1,23 +1,33 @@
 macro_rules! warn {
    ($fmt:literal, $ex:expr) => {{
        use console::{style, Emoji};
+        use std::env;
        let formatstr = format!($fmt, $ex);
-        println!(
-            "{} {}",
-            style(Emoji("⚠️ ", "!")).red(),
-            style(formatstr).red()
-        );
+        if env::var("NO_EMOJI").is_ok() {
+            println!("{} {}", style("!").red(), style(formatstr).red());
+        } else {
+            println!(
+                "{} {}",
+                style(Emoji("⚠️ ", "!")).red(),
+                style(formatstr).red()
+            );
+        }
    }};
 }

 macro_rules! success {
    ($fmt:literal, $ex:expr) => {{
        use console::{style, Emoji};
+        use std::env;
        let formatstr = format!($fmt, $ex);
-        println!(
-            "{} {}",
-            style(Emoji("✅", "✓")).green(),
-            style(formatstr).green()
-        );
+        if env::var("NO_EMOJI").is_ok() {
+            println!("{} {}", style("✓").green(), style(formatstr).green());
+        } else {
+            println!(
+                "{} {}",
+                style(Emoji("✅", "✓")).green(),
+                style(formatstr).green()
+            );
+        }
    }};
 }
--- a/src/verify.rs
+++ b/src/verify.rs
@@ -1,11 +1,20 @@
 use crate::exercise::{CompiledExercise, Exercise, Mode, State};
 use console::style;
 use indicatif::ProgressBar;
+use std::env;

-pub fn verify<'a>(start_at: impl IntoIterator<Item = &'a Exercise>) -> Result<(), &'a Exercise> {
+// Verify that the provided container of Exercise objects
+// can be compiled and run without any failures.
+// Any such failures will be reported to the end user.
+// If the Exercise being verified is a test, the verbose boolean
+// determines whether or not the test harness outputs are displayed.
+pub fn verify<'a>(
+    start_at: impl IntoIterator<Item = &'a Exercise>,
+    verbose: bool,
+) -> Result<(), &'a Exercise> {
    for exercise in start_at {
        let compile_result = match exercise.mode {
-            Mode::Test => compile_and_test(&exercise, RunMode::Interactive),
+            Mode::Test => compile_and_test(&exercise, RunMode::Interactive, verbose),
            Mode::Compile => compile_and_run_interactively(&exercise),
            Mode::Clippy => compile_only(&exercise),
        };
@@ -21,11 +30,13 @@ enum RunMode {
    NonInteractive,
 }

-pub fn test(exercise: &Exercise) -> Result<(), ()> {
-    compile_and_test(exercise, RunMode::NonInteractive)?;
+// Compile and run the resulting test harness of the given Exercise
+pub fn test(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
+    compile_and_test(exercise, RunMode::NonInteractive, verbose)?;
    Ok(())
 }

+// Invoke the rust compiler without running the resulting binary
 fn compile_only(exercise: &Exercise) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
@@ -38,6 +49,7 @@ fn compile_only(exercise: &Exercise) -> Result<bool, ()> {
    Ok(prompt_for_completion(&exercise, None))
 }

+// Compile the given Exercise and run the resulting binary in an interactive mode
 fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
@@ -54,6 +66,7 @@ fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
        Err(output) => {
            warn!("Ran {} with errors", exercise);
            println!("{}", output.stdout);
+            println!("{}", output.stderr);
            return Err(());
        }
    };
@@ -63,7 +76,9 @@ fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
    Ok(prompt_for_completion(&exercise, Some(output.stdout)))
 }

-fn compile_and_test(exercise: &Exercise, run_mode: RunMode) -> Result<bool, ()> {
+// Compile the given Exercise as a test harness and display
+// the output if verbose is set to true
+fn compile_and_test(exercise: &Exercise, run_mode: RunMode, verbose: bool) -> Result<bool, ()> {
    let progress_bar = ProgressBar::new_spinner();
    progress_bar.set_message(format!("Testing {}...", exercise).as_str());
    progress_bar.enable_steady_tick(100);
@@ -73,7 +88,10 @@ fn compile_and_test(exercise: &Exercise, run_mode: RunMode) -> Result<bool, ()>
    progress_bar.finish_and_clear();

    match result {
-        Ok(_) => {
+        Ok(output) => {
+            if verbose {
+                println!("{}", output.stdout);
+            }
            success!("Successfully tested {}", &exercise);
            if let RunMode::Interactive = run_mode {
                Ok(prompt_for_completion(&exercise, None))
@@ -92,6 +110,8 @@ fn compile_and_test(exercise: &Exercise, run_mode: RunMode) -> Result<bool, ()>
    }
 }

+// Compile the given Exercise and return an object with information
+// about the state of the compilation
 fn compile<'a, 'b>(
    exercise: &'a Exercise,
    progress_bar: &'b ProgressBar,
@@ -118,22 +138,34 @@ fn prompt_for_completion(exercise: &Exercise, prompt_output: Option<String>) ->
        State::Pending(context) => context,
    };

+    let no_emoji = env::var("NO_EMOJI").is_ok();
+
+    let clippy_success_msg = if no_emoji {
+        "The code is compiling, and Clippy is happy!"
+    } else {
+        "The code is compiling, and 📎 Clippy 📎 is happy!"
+    };
+
    let success_msg = match exercise.mode {
        Mode::Compile => "The code is compiling!",
        Mode::Test => "The code is compiling, and the tests pass!",
-        Mode::Clippy => "The code is compiling, and 📎 Clippy 📎 is happy!",
+        Mode::Clippy => clippy_success_msg,
    };

-    println!("");
-    println!("🎉 🎉  {} 🎉 🎉", success_msg);
-    println!("");
+    println!();
+    if no_emoji {
+        println!("~*~ {} ~*~", success_msg)
+    } else {
+        println!("🎉 🎉  {} 🎉 🎉", success_msg)
+    }
+    println!();

    if let Some(output) = prompt_output {
        println!("Output:");
        println!("{}", separator());
        println!("{}", output);
        println!("{}", separator());
-        println!("");
+        println!();
    }

    println!("You can keep working on this exercise,");
@@ -141,12 +173,12 @@ fn prompt_for_completion(exercise: &Exercise, prompt_output: Option<String>) ->
        "or jump into the next one by removing the {} comment:",
        style("`I AM NOT DONE`").bold()
    );
-    println!("");
+    println!();
    for context_line in context {
        let formatted_line = if context_line.important {
            format!("{}", style(context_line.line).bold())
        } else {
-            format!("{}", context_line.line)
+            context_line.line.to_string()
        };

        println!(
--- a/tests/fixture/state/info.toml
+++ b/tests/fixture/state/info.toml
@@ -9,3 +9,10 @@ name = "pending_test_exercise"
 path = "pending_test_exercise.rs"
 mode = "test"
 hint = """"""
+
+[[exercises]]
+name = "finished_exercise"
+path = "finished_exercise.rs"
+mode = "compile"
+hint = """"""
+
--- a/tests/fixture/success/testSuccess.rs
+++ b/tests/fixture/success/testSuccess.rs
@@ -1,4 +1,5 @@
 #[test]
 fn passing() {
+    println!("THIS TEST TOO SHALL PASS");
    assert!(true);
 }
--- a/tests/integration_tests.rs
+++ b/tests/integration_tests.rs
@@ -24,7 +24,7 @@ fn fails_when_in_wrong_dir() {
 fn verify_all_success() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .arg("v")
+        .arg("verify")
        .current_dir("tests/fixture/success")
        .assert()
        .success();
@@ -34,7 +34,7 @@ fn verify_all_success() {
 fn verify_fails_if_some_fails() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .arg("v")
+        .arg("verify")
        .current_dir("tests/fixture/failure")
        .assert()
        .code(1);
@@ -44,7 +44,7 @@ fn verify_fails_if_some_fails() {
 fn run_single_compile_success() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "compSuccess"])
+        .args(&["run", "compSuccess"])
        .current_dir("tests/fixture/success/")
        .assert()
        .success();
@@ -54,7 +54,7 @@ fn run_single_compile_success() {
 fn run_single_compile_failure() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "compFailure"])
+        .args(&["run", "compFailure"])
        .current_dir("tests/fixture/failure/")
        .assert()
        .code(1);
@@ -64,7 +64,7 @@ fn run_single_compile_failure() {
 fn run_single_test_success() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "testSuccess"])
+        .args(&["run", "testSuccess"])
        .current_dir("tests/fixture/success/")
        .assert()
        .success();
@@ -74,7 +74,7 @@ fn run_single_test_success() {
 fn run_single_test_failure() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "testFailure"])
+        .args(&["run", "testFailure"])
        .current_dir("tests/fixture/failure/")
        .assert()
        .code(1);
@@ -84,7 +84,7 @@ fn run_single_test_failure() {
 fn run_single_test_not_passed() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "testNotPassed.rs"])
+        .args(&["run", "testNotPassed.rs"])
        .current_dir("tests/fixture/failure/")
        .assert()
        .code(1);
@@ -94,7 +94,7 @@ fn run_single_test_not_passed() {
 fn run_single_test_no_filename() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .arg("r")
+        .arg("run")
        .current_dir("tests/fixture/")
        .assert()
        .code(1);
@@ -104,7 +104,7 @@ fn run_single_test_no_filename() {
 fn run_single_test_no_exercise() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "compNoExercise.rs"])
+        .args(&["run", "compNoExercise.rs"])
        .current_dir("tests/fixture/failure")
        .assert()
        .code(1);
@@ -114,7 +114,7 @@ fn run_single_test_no_exercise() {
 fn get_hint_for_single_test() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["h", "testFailure"])
+        .args(&["hint", "testFailure"])
        .current_dir("tests/fixture/failure")
        .assert()
        .code(0)
@@ -131,10 +131,15 @@ fn all_exercises_require_confirmation() {
            file.read_to_string(&mut s).unwrap();
            s
        };
-        source.matches("// I AM NOT DONE").next().expect(&format!(
-            "There should be an `I AM NOT DONE` annotation in {:?}",
-            path
-        ));
+        source
+            .matches("// I AM NOT DONE")
+            .next()
+            .unwrap_or_else(|| {
+                panic!(
+                    "There should be an `I AM NOT DONE` annotation in {:?}",
+                    path
+                )
+            });
    }
 }

@@ -142,7 +147,7 @@ fn all_exercises_require_confirmation() {
 fn run_compile_exercise_does_not_prompt() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "pending_exercise"])
+        .args(&["run", "pending_exercise"])
        .current_dir("tests/fixture/state")
        .assert()
        .code(0)
@@ -153,9 +158,85 @@ fn run_compile_exercise_does_not_prompt() {
 fn run_test_exercise_does_not_prompt() {
    Command::cargo_bin("rustlings")
        .unwrap()
-        .args(&["r", "pending_test_exercise"])
+        .args(&["run", "pending_test_exercise"])
        .current_dir("tests/fixture/state")
        .assert()
        .code(0)
        .stdout(predicates::str::contains("I AM NOT DONE").not());
 }
+
+#[test]
+fn run_single_test_success_with_output() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["--nocapture", "run", "testSuccess"])
+        .current_dir("tests/fixture/success/")
+        .assert()
+        .code(0)
+        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS"));
+}
+
+#[test]
+fn run_single_test_success_without_output() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["run", "testSuccess"])
+        .current_dir("tests/fixture/success/")
+        .assert()
+        .code(0)
+        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS").not());
+}
+
+#[test]
+fn run_rustlings_list() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["list"])
+        .current_dir("tests/fixture/success")
+        .assert()
+        .success();
+}
+
+#[test]
+fn run_rustlings_list_no_pending() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["list"])
+        .current_dir("tests/fixture/success")
+        .assert()
+        .success()
+        .stdout(predicates::str::contains("Pending").not());
+}
+
+#[test]
+fn run_rustlings_list_both_done_and_pending() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["list"])
+        .current_dir("tests/fixture/state")
+        .assert()
+        .success()
+        .stdout(predicates::str::contains("Done").and(predicates::str::contains("Pending")));
+}
+
+#[test]
+fn run_rustlings_list_without_pending() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["list", "--solved"])
+        .current_dir("tests/fixture/state")
+        .assert()
+        .success()
+        .stdout(predicates::str::contains("Pending").not());
+}
+
+#[test]
+fn run_rustlings_list_without_done() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["list", "--unsolved"])
+        .current_dir("tests/fixture/state")
+        .assert()
+        .success()
+        .stdout(predicates::str::contains("Done").not());
+}