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 _option_suite(self, value):
        opt = Optional(value)
        self.assert_(isinstance(opt, Optional))
        self.assert_(isinstance(deoption(opt), type(value)))
        self.assertEqual(deoption(opt), value)