def get_input_embeddings(self):
        """
        Returns the model's input embeddings.

        Returns:
            :obj:`nn.Module`:
                A torch module mapping vocabulary to hidden states.
        """
        base_model = getattr(self, self.base_model_prefix, self)
        if base_model is not self:
            return base_model.get_input_embeddings()
        else:
            raise NotImplementedError

        Returns the model's input embeddings.

        Returns:
            :obj:`nn.Module`:
                A torch module mapping vocabulary to hidden states.
        
xtune/src/transformers/modeling_utils.py