code: def require_backward(tensor):
      """
      Marks a tensor as a leaf in the adjoint graph.
      """
      tensor._pyro_backward = _LeafBackward(tensor)
  
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 1 for calling a global function with example usage: require_backward(tensor) without return types