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 __init__(self, config_d, path=None, resolver=None):
        super().__init__(path=path, resolver=resolver)
        self._collection = {}
        for key, value in config_d.items():
            self._collection[key] = self._from_python(key, value)