code: def test_byte(self):
      self._dll.tf_b.restype = c_byte
      self._dll.tf_b.argtypes = (c_byte,)
      self.assertEqual(self._dll.tf_b(-126), -42)
      self.assertEqual(self.S(), -126)
  
imports: import unittest
  from ctypes import *
  from ctypes.test import need_symbol
  import _ctypes_test
label_desc: Use image node_id 3 for calling the CFunctions obj's underlying member method code with example usage: obj.test_byte() without return types