code: def testStringConversion(self):
      cluster_spec = server_lib.ClusterSpec(
          {
              "ps": ["ps0:1111"],
              "worker": ["worker0:3333", "worker1:4444"],
          }
      )
  
      expected_str = (
          "ClusterSpec({'ps': ['ps0:1111'], 'worker': ['worker0:3333', "
          "'worker1:4444']})"
      )
      self.assertEqual(expected_str, str(cluster_spec))
  
imports: import time
  import numpy
  from tensorflow.core.protobuf import cluster_pb2
  from tensorflow.core.protobuf import config_pb2
  from tensorflow.core.protobuf import tensorflow_server_pb2
  from tensorflow.python.client import session
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors_impl
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import data_flow_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import variable_v1
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import test
  from tensorflow.python.training import input
  from tensorflow.python.training import queue_runner_impl
  from tensorflow.python.training import server_lib
  from tsl.protobuf import rpc_options_pb2
label_desc: Use image node_id 1 for calling the ClusterSpecTest obj's underlying member method code with example usage: obj.testStringConversion() without return types