old_contents: import unittest
  
  if sys.platform.startswith('darwin'):
      from nativeconfig.config import NSUserDefaultsConfig
      from test.config import TestConfigMixin
  
  
      class MyNSUserDefaultsConfig(NSUserDefaultsConfig):
          pass
  
  
      class TestMemoryConfig(unittest.TestCase, TestConfigMixin):
          CONFIG_TYPE = MyNSUserDefaultsConfig
  
          def tearDown(self):
              try:
                  c = self.CONFIG_TYPE.get_instance()
                  c.del_value_for_option_name('FirstName')
                  c.del_value_for_option_name('LastName')
                  c.del_value_for_option_name('LuckyNumber')
              except OSError:
                  pass
  
              TestConfigMixin.tearDown(self)
  
          def test_config_is_created_if_not_found(self):
              pass
  
new_contents: import sys
  import unittest
  
  if sys.platform.startswith('darwin'):
      from nativeconfig.config import NSUserDefaultsConfig
      from test.config import TestConfigMixin
  
  
      class MyNSUserDefaultsConfig(NSUserDefaultsConfig):
          pass
  
  
      class TestMemoryConfig(unittest.TestCase, TestConfigMixin):
          CONFIG_TYPE = MyNSUserDefaultsConfig
  
          def tearDown(self):
              try:
                  c = self.CONFIG_TYPE.get_instance()
                  c.del_value_for_option_name('FirstName')
                  c.del_value_for_option_name('LastName')
                  c.del_value_for_option_name('LuckyNumber')
              except OSError:
                  pass
  
              TestConfigMixin.tearDown(self)
  
          def test_config_is_created_if_not_found(self):
              pass
  
subject: Add missing import of sys.