errors exercise: improve instructions, add a challenge

exercise/errors/src/main.rs

@@ -3,6 +3,7 @@
 use aquarium::Dolphin;
 
 // (You already did #1 in lib.rs, right?)
+//
 // 2a. Uncomment and finish the play_time function below
 // - Bring anyhow::Result into scope with a `use` statement
 // - Have the play_time function return a `Result<Vec<String>>`. The vector of Strings will
@@ -10,18 +11,16 @@ use aquarium::Dolphin;
 
 // fn play_time(dolphin: &Dolphin) -> ... {
 //     let mut responses = vec![];
-//     // 2b. There are three methods on the Dolphin struct:
-//     // - .say_your_name()
-//     // - .flip()
-//     // - .shake_hands()
+//     // 2b. Call the .say_your_name() method on `dolphin`, use `?` to unwrap the value, and push
+//     // the value onto the `responses` vector.
 //     //
-//     // For each of the three methods above:
-//     // - Call the method on `dolphin`, using the `?` operator to unwrap the value / return the error
-//     // - Push the unwrapped string onto the `responses` vector using the .push() method
-
 //     // let response = ...    // this can be done with an intermediate variable...
 //     // responses.push( ... ) // ...or all on one line. Either way is fine!
-
+//     //
+//     // 2c. Do the same thing as #2b for the .flip() method
+//     //
+//     // 2d. Do the same thing as #2b for the .shake_hands() method
+//
 //     Ok(responses)
 // }
 
@@ -49,6 +48,9 @@ fn main() {
         },
     ];
     for dolphin in &dolphins {
+        // Challenge: Change main() so that it returns a Result, and instead of handling the error
+        // that play_time returns, use the try operator to only handle the success condition. How
+        // does the output of the program change?
         match play_time(dolphin) {
             Ok(responses) => {
                 println!("{} did a FABULOUS PERFORMANCE!", dolphin.name);