public function create(callable $callback = null): string
    {
        $_csrf = $this->c::uuidV4();

        if (isset($callback)) {
            $callback($_csrf);
            return $_csrf;
        }
        if ($this->c::isActiveSession()) {
            return $_SESSION['_csrf'] = $_csrf;
        }
        throw $this->c::issue('No storage handler.');
    }