_target_encoder和_context_encoder分别用于什么情况呀

请问node2vec.py 里的_target_encoder和_context_encoder分别用于什么情况呀？我看它俩都是 encoders.ShallowEncoder() 初始化参数也一模一样;
另外encoders.ShallowEncoder里__init__里有dim表示embedding_size,还有一个参数embedding_dim，这两个dim用于什么情况呢？
最后还想问一下combiner="add"和combiner=“concat", 这两个的用于什么场景呢？
感谢开源与解答！

Start with node2vec.py and encoders.ShallowEncoder.__init__ to trace how _target_encoder, _context_encoder, dim, embedding_dim, and combiner are used. Compare their call sites and existing examples, then document the distinct use cases and parameter meanings so each question has a clear answer.

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