code: def testChangeProcessingModeAfterRestart(self):
      cluster = data_service_test_base.TestCluster(num_workers=1)
      num_elements = 100
      range_dataset = dataset_ops.Dataset.range(num_elements)
      ds = range_dataset.apply(
          data_service_ops.distribute(
              processing_mode=data_service_ops.ShardingPolicy.OFF,
              service=cluster.dispatcher_address(),
              job_name="test",
          )
      )
      iterator = iter(ds)
      for i in range(num_elements // 2):
          self.assertEqual(i, next(iterator).numpy())
      cluster.restart_dispatcher()
      ds = range_dataset.apply(
          data_service_ops.distribute(
              processing_mode=data_service_ops.ShardingPolicy.DYNAMIC,
              service=cluster.dispatcher_address(),
              job_name="test",
          )
      )
      with self.assertRaisesOpError(
          "Tried to create job with name test, but found an existing job with "
          "different parameters"
      ):
          next(iter(ds)).numpy()
  
imports: import multiprocessing
  import threading
  import time
  from absl.testing import parameterized
  from tensorflow.python.data.experimental.kernel_tests.service import test_base
  from tensorflow.python.data.experimental.ops import data_service_ops
  from tensorflow.python.data.kernel_tests import test_base
  from tensorflow.python.data.ops import dataset_ops
  from tensorflow.python.framework import combinations
  from tensorflow.python.framework import dtypes
  from tensorflow.python.ops import array_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 15 for calling the FaultToleranceTest obj's underlying member method code with example usage: obj.testChangeProcessingModeAfterRestart() without return types