Rust Result Get Value. The Future trait from futures represents an asynchronous operation that can fail or succeed producing a value either way. Result is annotated with the must_use attribute which will cause the compiler to issue a warning when a Result value is ignored.
Maps a Result to Result by applying a function to a contained Ok value leaving an Err value untouched. This means that you as the programmer must handle the case when an Option is None instead of Somet. Zero-cost futures in Rust.
Otherwise the final result remains None.
In fact case analysis is the only way to get at the value stored inside an Option. Print the numbers on each line of a string multiplied by two. This means that you as the programmer must handle the case when an Option is None instead of Somet. Maps a Result to Result by applying a function to a contained Ok value leaving an Err value untouched.