src/transformers/models/deit/modeling_tf_deit.py/TFDeiTMainLayer/get_head_mask
class TFDeiTMainLayer:    def get_head_mask(self, head_mask):
        if head_mask is not None:
            raise NotImplementedError
        else:
            head_mask = [None] * self.config.num_hidden_layers

        return head_mask