code: def test_dict_update(self):
      update = _testcapi.dict_update
      for cls1 in dict, DictSubclass:
          for cls2 in dict, DictSubclass, UserDict:
              dct = cls1({"a": 1, "b": 2})
              update(dct, cls2({"b": 3, "c": 4}))
              self.assertEqual(dct, {"a": 1, "b": 3, "c": 4})
  
      self.assertRaises(AttributeError, update, {}, [])
      self.assertRaises(AttributeError, update, {}, 42)
      self.assertRaises(SystemError, update, UserDict(), {})
      self.assertRaises(SystemError, update, 42, {})
      self.assertRaises(SystemError, update, {}, NULL)
      self.assertRaises(SystemError, update, NULL, {})
  
imports: import unittest
  from collections import OrderedDict, UserDict
  from types import MappingProxyType
  from test import support
  import _testcapi
label_desc: Use image node_id 23 for calling the CAPITest obj's underlying member method code with example usage: obj.test_dict_update() without return types