'string|int'], default: '')] $key ): ?ReflectionReference {} /** * Returns unique identifier for the reference. The return value format is unspecified * * @link https://php.net/manual/en/reflectionreference.getid.php * @return int|string Returns an integer or string of unspecified format. */ #[Pure] public function getId(): string {} /** * ReflectionReference cannot be cloned * * @return void */ private function __clone(): void {} }