code: def testCountPs(self):
      cluster_spec = {
          "chief": ["127.0.0.1:1234"],
          "ps": ["127.0.0.1:1926", "127.0.0.1:3141"],
      }
      # A "ps" job shouldn't call this method.
      with self.assertRaisesRegex(
          ValueError, "Unexpected `task_type` 'ps'"
      ):
          multi_worker_util.worker_count(cluster_spec, task_type="ps")
  
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 4 for calling the NumWorkersTest obj's underlying member method code with example usage: obj.testCountPs() without return types