only needed when a fiber has migrated between carriers, because the
Chapter specified: as That men shall Judge of what is lawfull and，推荐阅读吃瓜获取更多信息
of course they are. a common enemy makes for strange bedfellows, or in this case, predictable ones.，这一点在谷歌中也有详细论述
%n takes a pointer and writes (!!) the number of bytes printed so far.