private function tokens(): void
    {
        foreach ($this->attributes as $attribute => $value) {
            switch ($attribute) {
                case Options::ATTRIBUTE_BOLD:
                    $this->tokens[] = Options::MARKDOWN_TOKEN_BOLD;
                    break;

                case Options::ATTRIBUTE_ITALIC:
                    $this->tokens[] = Options::MARKDOWN_TOKEN_ITALIC;
                    break;

                default:
                    break;
            }
        }
    }