code: def terminate(self):
      self._terminating = True
  
      # Terminate the thread first because it depends on the pool.
      if self._thread is not None:
          while self._thread.is_alive():
              self._thread.join(_response_time)
  
      if self._pool is not None:
          self._pool.terminate()
  
      self._thread = None
      self._pool = None
  
imports: from __future__ import division
  import datetime
  import multiprocessing
  from multiprocessing import sharedctypes
  import signal
  import sys
  import threading
  import warnings
  import numpy
  import six
  from chainer.dataset import iterator
  from chainer.iterators import _statemachine
  from chainer.iterators.order_samplers import ShuffleOrderSampler
label_desc: Use image node_id 2 for calling the _PrefetchLoop obj's underlying member method code with example usage: obj.terminate() without return types