A so-called "planetary nebula" is a confusing misnomer because these clouds have nothing to do with planets. As a medium-size star nears the end, it puffs out into a red giant — about 100 to 1,000 times its original size — eventually engulfing the space around it, including any nearby worlds.
block: Writes wait until buffer space is available. Use when you trust the producer to await writes properly.
，这一点在heLLoword翻译官方下载中也有详细论述
.pipeTo(slowSink); // Buffer grows without bound
// 每轮将最大值"冒泡"到末尾，所以范围逐渐缩小
Beth Alaw WilliamsBBC Wales