code: def perturb(self, inp: Tensor) -> Tensor:
      mask = torch.ones_like(inp)
      mask[:, self.count % mask.shape[1]] = 0.0
      self.count += 1
      return mask * inp
  
imports: import collections
  from typing import List
  import torch
  from captum.robust import AttackComparator, FGSM
  from tests.helpers.basic import assertTensorAlmostEqual, BaseTest
  from tests.helpers.basic_models import BasicModel, BasicModel_MultiLayer
  from torch import Tensor
label_desc: Use image node_id 2 for calling the SamplePerturb obj's underlying member method code with example usage: obj.perturb(inp) and returns: unknown