code: def n_episodes(self):
      return len(self.episodic_memory)
  
file_path: pfrl/pfrl/replay_buffers/episodic.py
imports: import collections
  import pickle
  from typing import Optional
  from pfrl.collections.random_access_queue import RandomAccessQueue
  from pfrl.replay_buffer import AbstractEpisodicReplayBuffer, random_subseq
label_desc: Use image node_id 6 for calling the EpisodicReplayBuffer obj's underlying member method code with example usage: obj.n_episodes() and returns: len