code: def test_create_or_load_study_no_study_config(self, mock_discovery):
      mock_get_study = mock.MagicMock()
      mock_discovery.build_from_document.return_value.projects().locations().studies().get = (
          mock_get_study
      )
  
      client = vizier_client.create_or_load_study(
          project_id=self._project_id,
          region=self._region,
          study_id=self._study_id,
      )
  
      self.assertIsInstance(client, vizier_client._VizierClient)
  
      _, mock_kwargs = mock_discovery.build_from_document.call_args
      self.assertIn("service", mock_kwargs)
      self.assertIsInstance(mock_kwargs["service"], dict)
      self.assertEqual(
          mock_kwargs["service"]["rootUrl"],
          # Regional endpoint must be specified for Vizier client.
          "https://us-central1-ml.googleapis.com/",
      )
  
      mock_get_study.assert_called_with(
          name="projects/{}/locations/{}/studies/{}".format(
              self._project_id, self._region, self._study_id
          )
      )
  
imports: from googleapiclient import errors
  import httplib2
  import mock
  import tensorflow
  from tensorflow_cloud.tuner import vizier_client
label_desc: Use image node_id 3 for calling the VizierClientTest obj's underlying member method code with example usage: obj.test_create_or_load_study_no_study_config(mock_discovery) without return types