construct target encoder

[PeterZ163426]

I would like to ask target_encoder = self._get_target_encoder() here, isn’t the online encoder copied directly?（target_encoder = copy.deepcopy(self.online_encoder) ） I don’t feel that momentum is used. Maybe because I am not familiar with python syntax, but after searching the Internet for a long time, I don’t know where the problem is, so I want to know if anyone can help me.