code: def testParallelWorkersShutdownFun(self):
      workspace.ResetWorkspace()
  
      queue = create_queue()
      dummy_worker = create_worker(queue, str)
      workspace.FeedBlob("data", "not shutdown")
  
      def shutdown_fun():
          workspace.FeedBlob("data", "shutdown")
  
      worker_coordinator = parallel_workers.init_workers(
          dummy_worker, shutdown_fun=shutdown_fun
      )
      worker_coordinator.start()
  
      self.assertTrue(worker_coordinator.stop())
  
      data = workspace.FetchBlob("data")
      self.assertEqual(
          data, b"shutdown", "Got unexpected value " + str(data)
      )
  
file_path: pytorch/caffe2/python/parallel_workers_test.py
imports: import unittest
  from caffe2.python import workspace, core
  import caffe2.python.parallel_workers
label_desc: Use image node_id 3 for calling the ParallelWorkersTest obj's underlying member method code with example usage: obj.testParallelWorkersShutdownFun() without return types