code: def testDispatcherNumWorkers(self):
      dispatcher = server_lib.DispatchServer()
      self.assertEqual(0, dispatcher._num_workers())
      worker1 = (
          server_lib.WorkerServer(  # pylint: disable=unused-variable
              server_lib.WorkerConfig(dispatcher._address)
          )
      )
      self.assertEqual(1, dispatcher._num_workers())
      worker2 = (
          server_lib.WorkerServer(  # pylint: disable=unused-variable
              server_lib.WorkerConfig(dispatcher._address)
          )
      )
      self.assertEqual(2, dispatcher._num_workers())
  
imports: import logging
  import tempfile
  import threading
  import unittest
  from tensorflow.python.data.experimental.service import server_lib
  from tensorflow.python.framework import errors
  from tensorflow.python.platform import test
  from tensorflow.python.profiler import profiler_client
label_desc: Use image node_id 16 for calling the ServerLibTest obj's underlying member method code with example usage: obj.testDispatcherNumWorkers() without return types