class_docstr: A regular replay buffer which stores transition without any additional structure
docstr: Get the mean reward in the replay buffer
  :return: the mean reward
docstr_tok: ["Get","the","mean","reward","in","the","replay","buffer",":","return",":","the","mean","reward"]
code: def mean_reward(self) -> np.ndarray:
      """
      Get the mean reward in the replay buffer
      :return: the mean reward
      """
      self.reader_writer_lock.lock_writing()
  
      mean = np.mean(
          [transition.reward for transition in self.transitions]
      )
  
      self.reader_writer_lock.release_writing()
  
      return mean
  
imports: from typing import List, Tuple, Union
  import pickle
  import random
  import math
  import numpy
  from rl_coach.core_types import Transition
  from rl_coach.logger import screen
  from rl_coach.memories.memory import Memory, MemoryGranularity, MemoryParameters
  from rl_coach.utils import ReaderWriterLock, ProgressBar
label_desc: Use image node_id 12 for calling the ExperienceReplay obj's underlying member method code with example usage: obj.mean_reward() and returns: mean