04/Traits/07_Deref std::String::trim

[egreglee]

04/Traits/07_Deref says:

// TODO: whenever title and description are returned via their accessor methods, they
// should be normalized—i.e. leading and trailing whitespace should be removed.
// There is a method in Rust's standard library that can help with this, but you won't
// find it in the documentation for String.
// Can you figure out where it is defined and how to use it?

This method appears to be in String:

std::String::trim