code: def __init__(self, datadir, fs):
      self.datadir = datadir
      self.fs = fs
  
imports: import binascii
  import collections
  import os
  import pickle
  from datetime import datetime
  from struct import calcsize, pack, unpack
  from pfrl.collections.random_access_queue import RandomAccessQueue
label_desc: Use image node_id 1 to create a new _ChunkReader object from inherited base classes: object with example: obj = _ChunkReader(datadir, fs)