Macro ward 

macro_rules! ward {
    ($o:expr) => { ... };
    ($o:expr, else $body:block) => { ... };
    ($o:expr, $early:stmt) => { ... };
}

Returns the contents of a Option<T>’s Some(T), otherwise it returns early from the function. Can alternatively have an else branch, or an alternative “early return” statement, like break or continue for loops.