code: def backward(self, req, out_grad, in_data, out_data, in_grad, aux):
      for i in range(len(in_grad)):
          self.assign(in_grad[i], req[i], 0)
  
imports: from __future__ import print_function
  import sys
  import mxnet
  import numpy
  import datetime
  from distutils.util import strtobool
  from ..config import config, generate_config
  from ..processing.generate_anchor import generate_anchors, anchors_plane
  from ..processing.bbox_transform import bbox_overlaps, bbox_transform, landmark_transform
label_desc: Use image node_id 5 for calling the CascadeRefineOperator obj's underlying member method code with example usage: obj.backward(req, out_grad, in_data, out_data, in_grad, aux) without return types