Traits

Here you have pets - which all implement the MakeSound trait.

But a reckless dev forgot to implement the trait for the pets and just left a todo!() for you.

He may have noticed his mistake, if he would just have called

cargo test

as this would have showed him the failed tests.

Can you correct his mistakes? He will be very thankful.

TL;DR: Make the tests pass ;) - And by make them pass we mean not deleting the asserts.