def _forward_feature(self, inputs):
        """Forward function for feature maps before classifying each pixel with
        ``self.cls_seg`` fc.

        Args:
            inputs (list[Tensor]): List of multi-level img features.

        Returns:
            feats (Tensor): A tensor of shape (batch_size, self.channels,
                H, W) which is feature map for last layer of decoder head.
        """
        x = self._transform_inputs(inputs)
        feats = self.convs(x)
        if self.concat_input:
            feats = self.conv_cat(torch.cat([x, feats], dim=1))
        return feats
Forward function for feature maps before classifying each pixel with
        ``self.cls_seg`` fc.

        Args:
            inputs (list[Tensor]): List of multi-level img features.

        Returns:
            feats (Tensor): A tensor of shape (batch_size, self.channels,
                H, W) which is feature map for last layer of decoder head.
        
segmentation/mmseg_custom/models/decode_heads/fcn_head.py