public function remove(string ...$tokens)
    {
        if (count($tokens) === 0) {
            return;
        }
        if (count($this->tokens) === 0) {
            return;
        }
        foreach ($tokens as $t) {
            $i = array_search($t, $this->tokens);
            if ($i === false) {
                continue;
            }
            array_splice($this->tokens, $i, 1);
        }
        $this->setAttributeValue();
    }