code: def test_save_and_load(self):
      capacity = self.capacity
  
      tempdir = tempfile.mkdtemp()
  
      rbuf = replay_buffer.EpisodicReplayBuffer(capacity)
  
      transs = [
          dict(
              state=n,
              action=n + 10,
              reward=n + 20,
              next_state=n + 1,
              next_action=n + 11,
              is_state_terminal=False,
          )
          for n in range(5)
      ]
  
      # Add two episodes
      rbuf.append(**transs[0])
      rbuf.append(**transs[1])
      rbuf.stop_current_episode()
  
      rbuf.append(**transs[2])
      rbuf.append(**transs[3])
      rbuf.append(**transs[4])
      rbuf.stop_current_episode()
  
      self.assertEqual(len(rbuf), 5)
      self.assertEqual(rbuf.n_episodes, 2)
  
      # Save
      filename = os.path.join(tempdir, "rbuf.pkl")
      rbuf.save(filename)
  
      # Initialize rbuf
      rbuf = replay_buffer.EpisodicReplayBuffer(capacity)
  
      # Of course it has no transition yet
      self.assertEqual(len(rbuf), 0)
  
      # Load the previously saved buffer
      rbuf.load(filename)
  
      # Sampled transitions are exactly what I added!
      s5 = rbuf.sample(5)
      self.assertEqual(len(s5), 5)
      for t in s5:
          assert len(t) == 1
          n = t[0]["state"]
          self.assertIn(n, range(5))
          self.assertEqual(t[0], transs[n])
  
      # And sampled episodes are exactly what I added!
      s2e = rbuf.sample_episodes(2)
      self.assertEqual(len(s2e), 2)
      if s2e[0][0]["state"] == 0:
          self.assertEqual(s2e[0], [transs[0], transs[1]])
          self.assertEqual(s2e[1], [transs[2], transs[3], transs[4]])
      else:
          self.assertEqual(s2e[0], [transs[2], transs[3], transs[4]])
          self.assertEqual(s2e[1], [transs[0], transs[1]])
  
      # Sizes are correct!
      self.assertEqual(len(rbuf), 5)
      self.assertEqual(rbuf.n_episodes, 2)
  
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 2 for calling the TestEpisodicReplayBuffer obj's underlying member method code with example usage: obj.test_save_and_load() without return types