code: def test_append_and_sample(self):
      capacity = self.capacity
      num_steps = self.num_steps
      rbuf = replay_buffers.ReplayBuffer(capacity, num_steps)
  
      assert len(rbuf) == 0
  
      # Add one and sample one
      correct_item = collections.deque([], maxlen=num_steps)
      for _ in range(num_steps):
          trans1 = dict(
              state=0,
              action=1,
              reward=2,
              next_state=3,
              next_action=4,
              is_state_terminal=False,
          )
          correct_item.append(trans1)
          rbuf.append(**trans1)
      assert len(rbuf) == 1
      s1 = rbuf.sample(1)
      assert len(s1) == 1
      assert s1[0] == list(correct_item)
  
      # Add two and sample two, which must be unique
      correct_item2 = copy.deepcopy(correct_item)
      trans2 = dict(
          state=1,
          action=1,
          reward=2,
          next_state=3,
          next_action=4,
          is_state_terminal=False,
      )
      correct_item2.append(trans2)
      rbuf.append(**trans2)
      assert len(rbuf) == 2
      s2 = rbuf.sample(2)
      assert len(s2) == 2
      if s2[0][num_steps - 1]["state"] == 0:
          assert s2[0] == list(correct_item)
          assert s2[1] == list(correct_item2)
      else:
          assert s2[1] == list(correct_item)
          assert s2[0] == list(correct_item2)
  
imports: import collections
  import copy
  import os
  import tempfile
  import unittest
  import numpy
  import pytest
  import torch
  from pfrl import replay_buffer, replay_buffers
label_desc: Use image node_id 2 for calling the TestReplayBuffer obj's underlying member method code with example usage: obj.test_append_and_sample() without return types