Result
We've seen that the Option enum can be used as a return value from functions
that may fail, where None can be returned to indicate failure. However,
sometimes it is important to express why an operation failed. To do this we
have the Result enum.
The Result<T, E> enum has two variants:
Ok(value)which indicates that the operation succeeded, and wraps thevaluereturned by the operation. (valuehas typeT)Err(why), which indicates that the operation failed, and wrapswhy, which (hopefully) explains the cause of the failure. (whyhas typeE)