src/transformers/models/lxmert/modeling_lxmert.py/LxmertAttention/transpose_for_scores
class LxmertAttention:    def transpose_for_scores(self, x):
        new_x_shape = x.size()[:-1] + (
            self.num_attention_heads,
            self.attention_head_size,
        )
        x = x.view(*new_x_shape)
        return x.permute(0, 2, 1, 3)