fn optional_to_result(opt: ?int, msg: string) - Result<int {
a constructor with implementation (user-defined constructor)
。PDF资料对此有专业解读
ilso的登顶就印证了这一点——其抖音占比高达79%，且保持203%的增长；天猫虽占比不高，却激增193.3%，最终实现超车。，更多细节参见新收录的资料
Not Equal: Every domino half in this space must have a completely different number of pips.