code: def backward(ctx, grad_out):
      return grad_out, None
  
imports: from enum import Enum
  import math
  import numpy
  import torch
  import warnings
  from .event_handling import combine_event_functions
label_desc: Use image node_id 2 for calling the _StitchGradient obj's underlying member method code with example usage: obj.backward(ctx, grad_out) and returns: grad_out,  None