These are not mainly aimed at savage chieftains who seal treaties with the proverbial X or a grunt, but at the infuriating inefficiencies of ink in the internet era.
Constantly asking if x in otherlist runs into geometric big-O inefficiencies; marching in parallel between two stably-sorted lists is more efficient. For example
不断地检查 if x in otherlist 会导致效率成 big-O 式几何级数递减；在两个固定排序的列表之间进行平行匹配的效率要高得多。