code: def tearDown(self) -> None:
      if self._reverb_server:
          self._reverb_server.stop()
          self._reverb_server = None
      super(ReverbVariableContainerTest, self).tearDown()
  
imports: from typing import Optional, Text, Tuple
  from absl import logging
  from absl.testing import parameterized
  import numpy
  import portpicker
  import reverb
  import tensorflow.compat.v2
  from tf_agents.experimental.distributed import reverb_variable_container
  from tf_agents.system import system_multiprocessing
  from tf_agents.typing import types
  from tf_agents.utils import nest_utils
  from tf_agents.utils import test_utils
label_desc: Use image node_id 2 for calling the ReverbVariableContainerTest obj's underlying member method code with example usage: obj.tearDown() without return types