def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
def myfunc(first, second=None, third=Optional(5), fourth=Optional(execute=list)):
            #Equivalent: second = deoption(second, 5)
            if isinstance(second, type(None)):
                second = 5