Added filename to top of .rs files

functions/functions1.rs

@@ -1,3 +1,4 @@
+// functions1.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {

functions/functions2.rs

@@ -1,3 +1,4 @@
+// functions2.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {

functions/functions3.rs

@@ -1,3 +1,4 @@
+// functions3.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {

functions/functions4.rs

@@ -1,3 +1,4 @@
+// functions4.rs
 // Make me compile! Scroll down for hints :)
 
 // This store is having a sale where if the price is an even number, you get

functions/functions5.rs

@@ -1,3 +1,4 @@
+// functions5.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {