code: def __init__(self, cachedir, variables):
      self._lock = threading.Lock()
      self._q = queue.Queue()
      self.file_name = None
      self._cachedir = cachedir
      self._variables = variables
      self._filereader = FileReader(self._cachedir)
      self._current_data = None
      self._thread = threading.Thread(target=self._worker)
      self._thread.setDaemon(True)
      self._thread.start()
      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 CachePrefetcher object from inherited base classes: object with example: obj = CachePrefetcher(cachedir, variables)