code: def forward(self, features):
      for idx, f in enumerate(self.in_features[::-1]):
          x = features[f]
          lateral_conv = self.lateral_convs[idx]
  
          if lateral_conv is None:
              y = self.output_convs[idx](x)
          else:
              cur_fpn = self.lateral_convs[idx](x)
              y = cur_fpn + F.interpolate(
                  y, size=cur_fpn.shape[-2:], mode="nearest"
              )
              y = self.output_convs[idx](y)
      return self.mask_features(y), None
  
imports: import math
  import copy
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddleseg.models import layers
  from paddleseg.cvlibs import manager, param_init
  from paddleseg.utils import utils
  from paddleseg.core.train import check_logits_losses
label_desc: Use image node_id 2 for calling the BasePixelDecoder obj's underlying member method code with example usage: obj.forward(features) and returns: self,  None