// 易错点4：栈空时返回1而非i+1 → 仅i=0时正确，i0时（如i=3）会返回1而非4
self._extract_text(soup.select_one("title"))，推荐阅读新收录的资料获取更多信息
。关于这个话题，PDF资料提供了深入分析
When one of the input cells changes, all the cells that depend on it need to react to that change — the aforementioned reactivity. In practice, though, this is the bare minimum requirement. When building reactive systems, there are usually some additional requirements we impose that make the problem harder:
货物用集装箱、货盘、车辆或者类似装运器具集装的，提单中载明装在此类装运器具中的货物件数或者其他货运单位数，视为前款规定的货物件数或者其他货运单位数；未载明的，每一装运器具视为一件货物或者一个其他货运单位。。业内人士推荐新收录的资料作为进阶阅读