if (n <= 1) return 0;
But that’s a lot of resetting! We can save a bunch of bandwidth by instead tracking the current foreground and background color in our renderer and only emitting a new color escape sequence when our desired color changes. This is an annoying amount of bookkeeping but it substantially cuts down on the amount of escape codes emitted.，推荐阅读搜狗输入法下载获取更多信息
Unconsumed bodies: Pull semantics mean nothing happens until you iterate. No hidden resource retention — if you don't consume a stream, there's no background machinery holding connections open.，更多细节参见快连下载安装
Optical-based smoke alarms use light instead. They are slightly better at detecting the large smoke particles created by slow, smouldering fires. When such particles enter a chamber in the device, they scatter light from a small light source, which is then picked up by a photoelectric sensor.