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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_protected_settings(self, settings_source):
 """ Attempt to retrieve protected settings from keyring if they are not already set. """

        user_backend = settings_source.get('keyring_backend')
        found_settings = dict()
        for setting_name in self.__PROTECTED_SETTINGS:
            # Nothing to do if the setting is already defined.
            if settings_source.get(setting_name):
                continue

            setting = None
            identifier = "%s.%s" % (self.__name__, setting_name)
            if hasattr(self, 'required') and setting_name in getattr(self, 'required'):
                setting = self.get_setting_from_keyring(identifier, user_backend)
            elif hasattr(self, setting_name):
                setting = self.get_setting_from_keyring(identifier, user_backend)
            if setting:
                found_settings.update({setting_name: setting})
        return found_settings