public static Maybe <T> Return <T>(T x) => Maybe.Just(x);
public static Maybe <TResult> Bind <T, TResult>(this Maybe <T> m, Func <T, Maybe <TResult> > f) =>
m.HasValue
? f(m.Value)
: Maybe.Nothing <TResult>();
public static Maybe <TResult> Map <T, TResult>(this Maybe <T> m, Func <T, TResult> f) =>
m.HasValue
? Maybe.Just(f(m.Value))
: Maybe.Nothing <TResult>();
