code: def setUp(self):
      super().setUp()
      self._mock_client = mock.MagicMock()
      self._mock_writer = mock.MagicMock()
      self._mock_client.trajectory_writer = self._mock_writer
      self._mock_writer.return_value = self._mock_writer
  
      self._table_name = "uniform_table"
      self._table = reverb.Table(
          self._table_name,
          max_size=100,
          sampler=reverb.selectors.Uniform(),
          remover=reverb.selectors.Fifo(),
          rate_limiter=reverb.rate_limiters.MinSize(1),
      )
      self._reverb_server = reverb.Server([self._table], port=None)
      self._reverb_client = self._reverb_server.localhost_client()
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import contextlib
  import functools
  import time
  from absl.testing import parameterized
  import mock
  import reverb
  from six.moves import range
  import tensorflow
  from tf_agents.drivers import py_driver
  from tf_agents.environments import parallel_py_environment
  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 tensor_spec
  from tf_agents.system import system_multiprocessing
  from tf_agents.trajectories import time_step
  from tf_agents.utils import test_utils
label_desc: Use image node_id 1 for calling the ReverbObserverTest obj's underlying member method code with example usage: obj.setUp() without return types