code: def test_save_and_load(self):
      capacity = self.capacity
      num_steps = self.num_steps
  
      tempdir = tempfile.mkdtemp()
  
      rbuf = replay_buffer.PrioritizedReplayBuffer(
          capacity, num_steps=num_steps
      )
  
      # Add two transitions
      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)
      correct_item2 = copy.deepcopy(correct_item)
      trans2 = dict(
          state=1,
          action=1,
          reward=2,
          next_state=3,
          next_action=4,
          is_state_terminal=True,
      )
      correct_item2.append(trans2)
      rbuf.append(**trans2)
  
      # Now it has two transitions
      self.assertEqual(len(rbuf), 2)
  
      # Save
      filename = os.path.join(tempdir, "rbuf.pkl")
      rbuf.save(filename)
  
      # Initialize rbuf
      rbuf = replay_buffer.PrioritizedReplayBuffer(
          capacity, num_steps=num_steps
      )
  
      # Of course it has no transition yet
      self.assertEqual(len(rbuf), 0)
  
      # Load the previously saved buffer
      rbuf.load(filename)
  
      # Now it has two transitions again
      self.assertEqual(len(rbuf), 2)
  
      # And sampled transitions are exactly what I added!
      s2 = rbuf.sample(2)
      del s2[0][0]["weight"]
      del s2[1][0]["weight"]
      if s2[0][num_steps - 1]["state"] == 0:
          self.assertEqual(s2[0], list(correct_item))
          self.assertEqual(s2[1], list(correct_item2))
      else:
          self.assertEqual(s2[0], list(correct_item2))
          self.assertEqual(s2[1], list(correct_item))
  
imports: import collections
  import copy
  import os
  import tempfile
  import unittest
  from chainer import testing
  import numpy
  from chainerrl import replay_buffer
label_desc: Use image node_id 4 for calling the TestPrioritizedReplayBuffer obj's underlying member method code with example usage: obj.test_save_and_load() without return types