code: def __len__(self):
      return self._curr_size
  
file_path: PARL/benchmark/fluid/DQN_variant/replay_memory.py
imports: import numpy
  import copy
  from collections import deque, namedtuple
label_desc: Use image node_id 5 for calling the ReplayMemory obj's underlying member method code with example usage: obj.__len__() and returns: self