def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def test_base_class_get_target_entity_html_strings(self):
        with self.assertRaisesRegex(
            NotImplementedError,
            'Subclasses of BaseSuggestion should implement'
            ' get_target_entity_html_strings.'):
            self.base_suggestion.get_target_entity_html_strings()