public function sure()
    {
        return !(substr($this->args[0], 0, 4) == 'http'
            || substr($this->args[0], 0, 3) == '../'
            || substr($this->args[0], 0, 3) == '\./'
            || substr($this->args[0], 0, 2) == './'
            || substr($this->args[0], 0, 1) == '/'
        );
    }