def vis_forward(self, feats: Tuple[Tensor]):
        """Forward the vis_head. The input is multi scale feature maps and the
        output is coordinates visibility.

        Args:
            feats (Tuple[Tensor]): Multi scale feature maps.

        Returns:
            Tensor: output coordinates visibility.
        """
        x = feats[-1]
        while len(x.shape) < 4:
            x.unsqueeze_(-1)
        x = self.vis_head(x)
        return x.reshape(-1, self.out_channels)
Forward the vis_head. The input is multi scale feature maps and the
        output is coordinates visibility.

        Args:
            feats (Tuple[Tensor]): Multi scale feature maps.

        Returns:
            Tensor: output coordinates visibility.
        
mmpose/mmpose/models/heads/hybrid_heads/vis_head.py