public function flag()
    {
        $args = func_get_args();
        $num = count($args);

        if ($num > 1) {
            $this->flags[$args[0]] = $args[1];

            return $this;
        }

        if (array_key_exists($args[0], $this->flags)) {
            return $this->flags[$args[0]];
        }
    }