code: def test_wait_for_stop(self):
      def waiter():
          self.assertTrue(self._manager.wait_for_stop())
  
      self._manager.thread_worker("worker", waiter)
      os.kill(os.getpid(), signal.SIGTERM)
      self.assertTrue(self._manager.wait_for_stop())
  
imports: import os
  import signal
  import threading
  import time
  from absl.testing import absltest
  from launchpad.launch import worker_manager
  import mock
label_desc: Use image node_id 3 for calling the WorkerManagerTest obj's underlying member method code with example usage: obj.test_wait_for_stop() without return types