src/transformers/models/maskformer/modeling_maskformer.py/MaskFormerPixelDecoder/forward
class MaskFormerPixelDecoder:    def forward(self, features: List[Tensor], output_hidden_states: bool = False) -> MaskFormerPixelDecoderOutput:
        fpn_features = self.fpn(features)
        # we use the last feature map
        last_feature_projected = self.mask_projection(fpn_features[-1])

        return MaskFormerPixelDecoderOutput(
            last_hidden_state=last_feature_projected, hidden_states=tuple(fpn_features) if output_hidden_states else ()
        )