code: def test_callwithresult(self):
      def process_result(result):
          return result * 2
  
      self._dll.tf_i.restype = process_result
      self._dll.tf_i.argtypes = (c_int,)
      self.assertEqual(self._dll.tf_i(42), 28)
      self.assertEqual(self.S(), 42)
      self.assertEqual(self._dll.tf_i(-42), -28)
      self.assertEqual(self.S(), -42)
  
imports: import _ctypes_test
  import ctypes
  import unittest
  from ctypes import CDLL, c_byte, c_ubyte, c_char, c_short, c_ushort, c_int, c_uint, c_long, c_ulong, c_longlong, c_ulonglong, c_float, c_double, c_longdouble
label_desc: Use image node_id 29 for calling the CFunctions obj's underlying member method code with example usage: obj.test_callwithresult() and returns: unknown