CI_Session::mark_as_flash PHP Method

    public function mark_as_flash($key)
    {
        if (is_array($key)) {
            for ($i = 0, $c = count($key); $i < $c; $i++) {
                if (!isset($_SESSION[$key[$i]])) {
                    return FALSE;
                }
            }
            $new = array_fill_keys($key, 'new');
            $_SESSION['__ci_vars'] = isset($_SESSION['__ci_vars']) ? array_merge($_SESSION['__ci_vars'], $new) : $new;
            return TRUE;
        }
        if (!isset($_SESSION[$key])) {
            return FALSE;
        }
        $_SESSION['__ci_vars'][$key] = 'new';
        return TRUE;
    }