code: def test_sizes(self):
      dll = CDLL(_ctypes_test.__file__)
      for i in range(1, 11):
          fields = [(f"f{f}", c_char) for f in range(1, i + 1)]
  
          class S(Structure):
              _fields_ = fields
  
          f = getattr(dll, f"TestSize{i}")
          f.restype = S
          res = f()
          for i, f in enumerate(fields):
              value = getattr(res, f[0])
              expected = bytes([ord("a") + i])
              self.assertEqual(value, expected)
  
imports: import _ctypes_test
  import ctypes
  import errno
  import sys
  import unittest
  from ctypes import CDLL, Structure, POINTER, pointer, sizeof, byref, _pointer_type_cache, c_void_p, c_char, c_int, c_long
  from test import support
  from ._support import Py_TPFLAGS_DISALLOW_INSTANTIATION, Py_TPFLAGS_IMMUTABLETYPE
label_desc: Use image node_id 1 for calling the ReturnStructSizesTestCase obj's underlying member method code with example usage: obj.test_sizes() without return types