Rust has a built in generic enum called Result that allows us to return a value that has the possibility of failing.
It is the idiomatic way in which the language does error handling.
enum Result<T, E> {
Ok(T),
Err(E),
}
Note that our generics type has multiple parameterized types separated by a comma.
This enum is so common, instances of the enum can be created anywhere with the enum variants Ok and Err.