code: def _report_pid(_):  # for testing
      return multiprocessing.current_process().pid
  
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 4 for calling a global function with example usage: _report_pid(_) and returns: multiprocessing