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 pop(self, key, default=None):
        value = self._collection.pop(key, default)
        if isinstance(value, Proxy):
            value = value.get()
        return value