code: def test_create_dataset_existing(self):
      with self.assertRaises(ValueError):
          self.api_workflow_client.create_dataset(
              dataset_name="dataset_1"
          )
  
imports: from typing import List
  import pytest
  from pytest_mock import MockerFixture
  from lightly.api import ApiWorkflowClient, api_workflow_datasets
  from lightly.openapi_generated.swagger_client.api import DatasetsApi
  from lightly.openapi_generated.swagger_client.models import Creator, DatasetCreateRequest, DatasetData, DatasetType
  from lightly.openapi_generated.swagger_client.rest import ApiException
  from tests.api_workflow import utils
  from tests.api_workflow.mocked_api_workflow_client import MockedApiWorkflowSetup
label_desc: Use image node_id 2 for calling the TestApiWorkflowDatasets obj's underlying member method code with example usage: obj.test_create_dataset_existing() without return types