public static A ifFail <A>(Fin <A> ma, A alternative) => ma.IfFail(alternative);
public static Unit ifFail <A>(Fin <A> ma, Action <Error> Left) => ma.IfFail(Left);
public static A ifFail <A>(Fin <A> ma, Func <Error, A> Fail) => ma.IfFail(Fail);