def forward(self, in_feat_list):
        """
        Args:
            in_feat_list (List(Tensor)): Such as [x2, x4, x8, x16, x32].
                x2, x4 and x8 are optional.
        Returns:
            out_feat_list (List(Tensor)): Such as [x2, x4, x8, x16, x32].
                x2, x4 and x8 are optional.
                The length of in_feat_list and out_feat_list are the same.
        """

        high_feat = self.cm(in_feat_list[-1])
        out_feat_list = []

        for i in reversed(range(len(in_feat_list))):
            low_feat = in_feat_list[i]
            arm = self.arm_list[i]
            high_feat = arm(low_feat, high_feat)
            out_feat_list.insert(0, high_feat)

        return out_feat_list

        Args:
            in_feat_list (List(Tensor)): Such as [x2, x4, x8, x16, x32].
                x2, x4 and x8 are optional.
        Returns:
            out_feat_list (List(Tensor)): Such as [x2, x4, x8, x16, x32].
                x2, x4 and x8 are optional.
                The length of in_feat_list and out_feat_list are the same.
        
paddleseg/models/pp_liteseg.py