code: def backward(self, inputs_val, logits_grad_val):
      rval = self.tfmodel.backward(
          self._to_numpy(inputs_val),
          self._to_numpy(logits_grad_val),
      )
      return self._to_torch(rval)
  
file_path: advertorch/advertorch_examples/attack_madry_et_al_models/madry_et_al_utils.py
imports: import os
  import sys
  from pathlib import Path
  import tensorflow
  import torch
  from advertorch.bpda import BPDAWrapper
  from advertorch_examples.utils import ROOT_PATH, mkdir
label_desc: Use image node_id 5 for calling the TorchWrappedModel obj's underlying member method code with example usage: obj.backward(inputs_val, logits_grad_val) and returns: self