General clean-up

Cleaned up some inconsistency in your line spacing, and removed:

* redundant ``()`` return types (Rust assumes them if no return type's explicitly given)
* ``contents`` variable binding - you can just directly match on the value without giving it a name
* redundant ``return`` statements - the return value of a function is, by default, the value of its final expression (following that with a semicolon means the actual final expression is empty, however, so be careful)

Hope that helps your Rust learning at least a little!