code: def process(self, message):
      target = self.target()
      assert message is not target, "memory leak"
      target._pyro_backward_result = message
      return ()
  
imports: import weakref
  from abc import ABCMeta, abstractmethod
  import torch
  from pyro.ops import packed
  from pyro.util import jit_iter
label_desc: Use image node_id 2 for calling the _LeafBackward obj's underlying member method code with example usage: obj.process(message) and returns: 