improve typestate pattern slides

src/idiomatic/leveraging-the-type-system/typestate-pattern.md

@@ -83,6 +83,7 @@ serialize struct start
   system.
 
   In the next slide, we will apply the **typestate pattern** to enforce correct
-  usage at compile time and make invalid states unrepresentable.
+  usage at compile time and make it impossible to call incompatible methods or
+  forget to do a required action.
 
 </details>

src/idiomatic/leveraging-the-type-system/typestate-pattern/typestate-advanced.md

@@ -60,9 +60,6 @@ impl SerializeList {
 
 - However, this introduces both **duplication** and **structural complexity**.
 
-  `SerializeStructProperty` and `SerializeList` now share similar logic (e.g.
-  adding strings, nested structs, or nested lists).
-
 - Even more critically, we now hit a **type system limitation**: we cannot
   cleanly express what `finish()` should return without duplicating variants for
   every nesting context (e.g. root, struct, list).

src/idiomatic/leveraging-the-type-system/typestate-pattern/typestate-example.md

@@ -17,7 +17,7 @@ struct SerializeStruct {
 
 impl Serializer {
     fn serialize_struct(mut self, name: &str) -> SerializeStruct {
-        let _ = writeln!(&mut self.output, "{name} {{");
+        writeln!(&mut self.output, "{name} {{").unwrap();
         SerializeStruct { serializer: self }
     }
 
@@ -28,7 +28,7 @@ impl Serializer {
 
 impl SerializeStruct {
     fn serialize_field(mut self, key: &str, value: &str) -> Self {
-        let _ = writeln!(&mut self.serializer.output, "  {key}={value};");
+        writeln!(&mut self.serializer.output, "  {key}={value};").unwrap();
         self
     }
 
@@ -62,8 +62,9 @@ fn main() {
 
 ```bob
 +------------+  serialize struct   +-----------------+
-| Serializer +-------------------->| SerializeStruct |<-------+
+| Serializer | ------------------> | SerializeStruct | <------+
-+--+---------+                     +-+-----+---------+        |
++------------+                     +-----------------+        |
+                                                              |
    |   ^                             |     |                  |
    |   |     finish struct           |     | serialize field  |
    |   +-----------------------------+     +------------------+
@@ -81,7 +82,7 @@ fn main() {
     related to serializing struct fields.
 
   - The original `Serializer` is no longer accessible — preventing us from
-    mixing modes (like writing a tuple or primitive mid-struct) or calling
+    mixing modes (such as starting another _struct_ mid-struct) or calling
     `finish()` too early.
 
   - Only after calling `.finish_struct()` do we receive the `Serializer` back.

src/idiomatic/leveraging-the-type-system/typestate-pattern/typestate-generics.md

@@ -176,7 +176,7 @@ fn main() {
 <details>
 
 - The full code for this example is available
-  [in the playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=48b106089ca600453f3ed00a0a31af26)
+  [in the playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=48b106089ca600453f3ed00a0a31af26).
 
 - By using generics to track the parent context, we can construct arbitrarily
   nested serializers that enforce valid transitions between struct, list, and
@@ -234,7 +234,7 @@ finish   |                       |    +-------------------------------+  struct
 - Of course, this pattern isn't a silver bullet. It still allows issues like:
   - Empty or invalid property names (which can be fixed using
     [the newtype pattern](../newtype-pattern.md))
-  - Duplicate property names (which could be tracked in `Struct<S>` or handled
+  - Duplicate property names (which could be tracked in `Struct<S>` and handled
     via `Result`)
 
 - If validation failures occur, we can also change method signatures to return a