code: def test_sample_single_episode(self):
      num_episodes = 1
      sequence_length = 100
      batch_size = 10
      num_steps = 5
      env = test_envs.EpisodeCountingEnv(
          steps_per_episode=sequence_length
      )
      # Insert only one episode in the RB.
      self._insert_random_data(
          env,
          num_steps=num_episodes * sequence_length,
          sequence_length=sequence_length,
      )
  
      replay = reverb_replay_buffer.ReverbReplayBuffer(
          self._data_spec,
          self._table_name,
          sequence_length=sequence_length,
          local_server=self._server,
      )
  
      dataset = replay.as_dataset(batch_size, num_steps=num_steps)
      n_samples = 0
      for sample, _ in dataset.take(10):
          n_samples += 1
          episode, step = sample.observation
          # The episode should always be 0.
          episode_id = tf.constant(
              0, dtype=episode.dtype, shape=episode.shape
          )
          # All elements in the same batch should belong to the same episode.
          self.assertAllEqual(episode_id, episode)
          for n in range(num_steps):
              # All elements in the batch should have consecutive steps.
              self.assertAllEqual(step[:, 0] + n, step[:, n])
      # Ensure we can actually sampled 10 times.
      self.assertEqual(10, n_samples)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import reverb
  import tensorflow
  from tf_agents.drivers import py_driver
  from tf_agents.environments import test_envs
  from tf_agents.policies import random_py_policy
  from tf_agents.replay_buffers import reverb_replay_buffer
  from tf_agents.replay_buffers import reverb_utils
  from tf_agents.specs import array_spec
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import trajectory
  from tf_agents.utils import common
  from tf_agents.utils import test_utils
label_desc: Use image node_id 11 for calling the ReverbReplayBufferTest obj's underlying member method code with example usage: obj.test_sample_single_episode() without return types