Convenience functions for working with Result
Check whether the result is Err without unwrapping it.
Turn a Result e a to an a, by applying the conversion
function specified to the e.
Convert a Result e a to a b by applying either a function
if the Result is an Err or a function if the Result is Ok.
Both of these functions must return the same type.
Combine a list of results into a single result (holding a list).
Check whether the result is
Okwithout unwrapping it.