code: def measure_required(self):
      return self.mem_size is 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 4 for calling the _PrefetchLoop obj's underlying member method code with example usage: obj.measure_required() and returns: unknown