code: def test_mixed_1(self):
      class X(Structure):
          _fields_ = [("a", c_byte, 4), ("b", c_int, 4)]
  
      if os.name == "nt":
          self.assertEqual(sizeof(X), sizeof(c_int) * 2)
      else:
          self.assertEqual(sizeof(X), sizeof(c_int))
  
imports: import _ctypes_test
  import os
  import unittest
  from ctypes import CDLL, Structure, sizeof, POINTER, byref, alignment, LittleEndianStructure, BigEndianStructure, c_byte, c_ubyte, c_char, c_char_p, c_void_p, c_wchar, c_uint32, c_uint64, c_short, c_ushort, c_int, c_uint, c_long, c_ulong, c_longlong, c_ulonglong
  from test import support
label_desc: Use image node_id 11 for calling the BitFieldTest obj's underlying member method code with example usage: obj.test_mixed_1() without return types