"It's up to you to make that decision... and let's face it, it's a small price to pay getting your gallbladder out if you're going to lose pounds."
3. 递归：对左右子数组递归执行1-2步，推荐阅读safew官方下载获取更多信息
``@receiver isNil ifTrue: ``@nilBlock -> ``@receiver ifNil: ``@nilBlockOr maybe with single backticks?，详情可参考同城约会
const n = prices.length;