code: def _assert_nested_variable_in_server(
      self, server_address: Optional[Text] = None
  ) -> None:
      # Create Python client.
      address = server_address or self._server_address
      client = reverb.Client(address)
      self.assertEqual(
          client.server_info()[
              reverb_variable_container.DEFAULT_TABLE
          ].current_size,
          1,
      )
  
      # Draw one sample from the server using the Python client.
      content = next(
          iter(
              client.sample(reverb_variable_container.DEFAULT_TABLE, 1)
          )
      )[
          0
      ].data  # pytype: disable=attribute-error  # strict_namedtuple_checks
      # Internally in Reverb the data is stored in the form of flat numpy lists.
      self.assertLen(content, 3)
      self.assertAllEqual(content[0], np.array(0, dtype=np.int64))
      self.assertAllClose(
          content[1], np.array([1, 1], dtype=np.float64)
      )
      self.assertAllEqual(
          content[2], np.array([[2], [3]], dtype=np.int32)
      )
  
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 19 for calling the ReverbVariableContainerTest obj's underlying member method code with example usage: obj._assert_nested_variable_in_server(server_address) without return types