code: def __init__(self, cachedir, num_threads, variables):
      self._variables = variables
      self._cache_prefetchers = [
          CachePrefetcher(cachedir, variables)
          for _ in range(num_threads)
      ]
      self._closed = False
      atexit.register(self.close)
  
imports: import atexit
  import csv
  import os
  import threading
  from collections import OrderedDict, deque
  from time import sleep
  import numpy
  from nnabla.config import nnabla_config
  from nnabla.logger import logger
  from nnabla.utils.communicator_util import current_communicator
  from six.moves import queue
  from .data_source import DataSource
  from .data_source_loader import FileReader, load
label_desc: Use image node_id 1 to create a new CacheReaderWithPrefetch object from inherited base classes: object with example: obj = CacheReaderWithPrefetch(cachedir, num_threads, variables)