class_docstr: Defines a common interface of replay buffer.
  
  You can append transitions to the replay buffer and later sample from it.
  Replay buffers are typically used in experience replay.
docstr: Sample n unique transitions from this replay buffer.
  
  Args:
      n (int): Number of transitions to sample.
  Returns:
      Sequence of n sampled transitions.
docstr_tok: ["Sample","n","unique","transitions","from","this","replay","buffer",".","Args",":","n","(","int",")",":","Number","of","transitions","to","sample",".","Returns",":","Sequence","of","n","sampled","transitions","."]
code: def sample(self, n):
      """Sample n unique transitions from this replay buffer.
  
      Args:
          n (int): Number of transitions to sample.
      Returns:
          Sequence of n sampled transitions.
      """
      raise NotImplementedError
  
imports: from abc import ABCMeta
  from abc import abstractmethod
  from abc import abstractproperty
  import itertools
  import numpy
  from chainerrl.misc.batch_states import batch_states
label_desc: Use image node_id 2 for calling the AbstractReplayBuffer obj's underlying member method code with example usage: obj.sample(n) without return types