code: def dummy_callback(self):
      from skorch.callbacks import Callback
  
      cb = Mock(spec=Callback)
      # make dummy behave like an estimator
      cb.get_params.return_value = {}
      cb.set_params = lambda **kwargs: cb
      return cb
  
imports: from unittest.mock import Mock
  import numpy
  import pytest
  import torch
  from scipy.special import expit
  from sklearn.base import clone
  from torch import nn
  from skorch.tests.conftest import INFERENCE_METHODS
label_desc: Use image node_id 2 for calling the TestNeuralNet obj's underlying member method code with example usage: obj.dummy_callback() and returns: cb