def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def test_execute(self):
        opt = Optional(None, execute=dict)
        self.assertEqual(deoption(opt), {})
        self.assertEqual(deoption(opt, execute=dict), {})
        self.assertEqual(deoption(None, execute=dict), {})