code: def get_grad(self):
      return self.perturbation.grad * self.mask
  
imports: import torch
  import torch.nn
  import torch.optim
  from tqdm.auto import tqdm
  from typing import List
  from sparse_layer import SparseNet
label_desc: Use image node_id 4 for calling the SparseAttackModule obj's underlying member method code with example usage: obj.get_grad() and returns: unknown