code: def test_1_A(self):
      class X(Structure):
          pass
  
      self.assertEqual(sizeof(X), 0)  # not finalized
      X._fields_ = []  # finalized
      self.assertRaises(AttributeError, setattr, X, "_fields_", [])
  
file_path: cpython/Lib/test/test_ctypes/test_struct_fields.py
imports: import unittest
  from ctypes import Structure, Union, sizeof, c_char, c_int
  from ._support import CField, Py_TPFLAGS_DISALLOW_INSTANTIATION, Py_TPFLAGS_IMMUTABLETYPE
label_desc: Use image node_id 1 for calling the StructFieldsTestCase obj's underlying member method code with example usage: obj.test_1_A() without return types