code: def forward(self, x):
      y = self.conv_block(x)
      if self.skip:
          res = x
          if self.downsample:
              res = self.conv_down(res)
          y = y + res
      return self.final_activation(y)
  
imports: from typing import List, Tuple
  import numpy
  import paddle
  import paddle.nn
  from paddle import Tensor
  from medicalseg.cvlibs import manager
label_desc: Use image node_id 2 for calling the Conv3DBlock obj's underlying member method code with example usage: obj.forward(x) and returns: self