code: def test_null_slots(self):
      # Test that NULL slots aren't a problem.
      name = self.name + "_null_slots"
      module = self.load_module_by_name(name)
      self.assertIsInstance(module, types.ModuleType)
      self.assertEqual(module.__name__, name)
  
imports: from test.test_importlib import abc, util
  import os.path
  import sys
  import types
  import unittest
  import warnings
  import importlib.util
  import importlib
  from test.support import MISSING_C_DOCSTRINGS
label_desc: Use image node_id 15 for calling the MultiPhaseExtensionModuleTests obj's underlying member method code with example usage: obj.test_null_slots() without return types