code: def n_hook_called(self):
      with self._lock:
          return self._hook_called.value
  
imports: import ctypes
  import io
  import multiprocessing
  import os
  import pickle
  import platform
  import sys
  import unittest
  import mock
  from chainer import datasets
  from chainer.datasets import pickle_dataset
  from chainer import testing
  from chainer import utils
label_desc: Use image node_id 2 for calling the ReaderMock obj's underlying member method code with example usage: obj.n_hook_called() and returns: self