class_docstr: Abstract class for Replay Buffer.
  
  Args:
      env_spec (EnvSpec): Environment specification.
      size_in_transitions (int): total size of transitions in the buffer
      time_horizon (int): time horizon of epsiode.
docstr: Sample a transition of batch_size.
  
  Args:
      batch_size(int): The number of transitions to be sampled.
docstr_tok: ["Sample","a","transition","of","batch_size",".","Args",":","batch_size","(","int",")",":","The","number","of","transitions","to","be","sampled","."]
code: def sample(self, batch_size):
      """Sample a transition of batch_size.
  
      Args:
          batch_size(int): The number of transitions to be sampled.
  
      """
      raise NotImplementedError
  
file_path: garage/src/garage/replay_buffer/replay_buffer.py
imports: import abc
  from abc import abstractmethod
  import numpy
label_desc: Use image node_id 3 for calling the ReplayBuffer obj's underlying member method code with example usage: obj.sample(batch_size) without return types