code: def forward(self, x, skip=None):
      x = self.up(x)
      if skip is not None:
          x = paddle.concat([x, skip], axis=1)
      x = self.conv1(x)
      x = self.conv2(x)
      return x
  
imports: import copy
  import math
  import numpy
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from medicalseg.cvlibs import manager
  from medicalseg.utils import load_pretrained_model
label_desc: Use image node_id 2 for calling the DecoderBlock obj's underlying member method code with example usage: obj.forward(x, skip) and returns: x