    def get_output_dim(self) -> int:
        """
        Returns the final output dimension that this `TokenEmbedder` uses to represent each
        token.  This is `not` the shape of the returned tensor, but the last element of that shape.
        """
        raise NotImplementedError
Returns the final output dimension that this `TokenEmbedder` uses to represent each
token.  This is `not` the shape of the returned tensor, but the last element of that shape.
allennlp/modules/token_embedders/token_embedder.py