code: def tearDown(self):
      if self._server:
          # Stop the Reverb server if it is running.
          self._server.stop()
          self._server = None
      super(ReverbReplayBufferTest, self).tearDown()
  
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 2 for calling the ReverbReplayBufferTest obj's underlying member method code with example usage: obj.tearDown() without return types