code: def test_everyone_has___loader__(self):
      # Issue #17098: all modules should have __loader__ defined.
      for name, module in sys.modules.items():
          if isinstance(module, types.ModuleType):
              with self.subTest(name=name):
                  self.assertTrue(
                      hasattr(module, "__loader__"),
                      "{!r} lacks a __loader__ attribute".format(name),
                  )
                  if self.machinery.BuiltinImporter.find_spec(name):
                      self.assertIsNot(module.__loader__, None)
                  elif self.machinery.FrozenImporter.find_spec(name):
                      self.assertIsNot(module.__loader__, None)
  
imports: from test.test_importlib import util
  import os.path
  import sys
  from test.support import import_helper
  from test.support import os_helper
  import types
  import unittest
label_desc: Use image node_id 1 for calling the StartupTests obj's underlying member method code with example usage: obj.test_everyone_has___loader__() without return types