遥遥领先不假，但不够完美也是真的。
A bullet strikes the back of his head, and he falls to the ground.
。关于这个话题，WPS下载最新地址提供了深入分析
Transforms don't execute until the consumer pulls. There's no eager evaluation, no hidden buffering. Data flows on-demand from source, through transforms, to the consumer. If you stop iterating, processing stops.
圖像來源，Oscar Wong/Getty Images