code: def test_checkretval(self):
      import _ctypes_test
  
      dll = CDLL(_ctypes_test.__file__)
      self.assertEqual(42, dll._testfunc_p_p(42))
  
      dll._testfunc_p_p.restype = CHECKED
      self.assertEqual("42", dll._testfunc_p_p(42))
  
      dll._testfunc_p_p.restype = None
      self.assertEqual(None, dll._testfunc_p_p(42))
  
      del dll._testfunc_p_p.restype
      self.assertEqual(42, dll._testfunc_p_p(42))
  
file_path: catboost/contrib/tools/python/src/Lib/ctypes/test/test_checkretval.py
imports: import unittest
  from ctypes import *
  from ctypes.test import need_symbol
label_desc: Use image node_id 1 for calling the Test obj's underlying member method code with example usage: obj.test_checkretval() without return types