code: def testRetainSparseJobWithNoMerging(self):
      base_cluster_spec = server_lib.ClusterSpec(
          {
              "worker": {
                  1: "worker0:2222",
                  3: "worker1:2222",
                  5: "worker2:2222",
              }
          }
      )
  
      base_cluster_resolver = cluster_resolver.SimpleClusterResolver(
          base_cluster_spec
      )
      union_cluster = cluster_resolver.UnionClusterResolver(
          base_cluster_resolver
      )
      cluster_spec = union_cluster.cluster_spec()
  
      expected_proto = """
      job { name: 'worker' tasks { key: 1 value: 'worker0:2222' }
                           tasks { key: 3 value: 'worker1:2222' }
                           tasks { key: 5 value: 'worker2:2222' } }
      """
      self._verifyClusterSpecEquality(cluster_spec, expected_proto)
  
imports: from tensorflow.python.client import session
  from tensorflow.python.distribute.cluster_resolver import cluster_resolver
  from tensorflow.python.eager import context
  from tensorflow.python.framework import config
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import test
  from tensorflow.python.training import server_lib
label_desc: Use image node_id 16 for calling the UnionClusterResolverTest obj's underlying member method code with example usage: obj.testRetainSparseJobWithNoMerging() without return types