code: def testTaskTypeNotFound(self):
      cluster_spec = {}
      with self.assertRaisesRegex(
          ValueError, "`task_type` 'worker' not found in cluster_spec."
      ):
          multi_worker_util.worker_count(
              cluster_spec, task_type="worker"
          )
  
imports: from tensorflow.core.protobuf import cluster_pb2
  from tensorflow.python.distribute import multi_worker_util
  from tensorflow.python.eager import test
  from tensorflow.python.training import server_lib
label_desc: Use image node_id 3 for calling the NumWorkersTest obj's underlying member method code with example usage: obj.testTaskTypeNotFound() without return types