Gets a setting for the key.

        :raise KeyError: If the key is not set and default isn't provided.

def get_setting(self, key, default=NOT_SET):
        """ Gets a setting for the key.

        :raise KeyError: If the key is not set and default isn't provided.
        """
        if self._arca is None:
            raise LazySettingProperty.SettingsNotReady
        return self._arca.settings.get(*self.get_settings_keys(key), default=default)