// **Exercise 08.6**: Write a subtraction function, and testcases for it. Decide for yourself how you want to handle negative results.
// For example, you may want to return an `Option`, to panic, or to return `0`.
// **Exercise 08.6**: Write a subtraction function, and testcases for it. Decide for yourself how you want to handle negative results.
// For example, you may want to return an `Option`, to panic, or to return `0`.