code: def test_list_models(self):
      sys.path.append(
          os.path.abspath("ts/tests/unit_tests/test_utils/")
      )
      module = importlib.import_module("dummy_class_model_service")
      classes = list_classes_from_module(module)
      assert len(classes) == 1
      assert classes[0].__name__ == "CustomService"
  
imports: import importlib
  import inspect
  import os
  import sys
  import types
  from collections import namedtuple
  import mock
  import pytest
  from ts.model_loader import ModelLoaderFactory, TsModelLoader
  from ts.model_service.model_service import SingleNodeService
  from ts.torch_handler.request_envelope.json import JSONEnvelope
  from ts.utils.util import list_classes_from_module
label_desc: Use image node_id 2 for calling the TestListModels obj's underlying member method code with example usage: obj.test_list_models() without return types