Macro if_return_result_from_ensure_ok 

macro_rules! if_return_result_from_ensure_ok {
    ([] $then:tt $no:tt) => { ... };
    ([(return_result_from_ensure_ok) $($modifiers:tt)*] $yes:tt $no:tt) => { ... };
    ([$other:tt $($modifiers:tt)*] $yes:tt $no:tt) => { ... };
}