syntax = "proto3"; // 指定使用proto3版本
Every fragment means promises created for read() calls, promises for backpressure coordination, intermediate buffer allocations, and { value, done } result objects – most of which become garbage almost immediately.
，这一点在搜狗输入法下载中也有详细论述
距离：孩子还小，离家近是核心指标，接送方便，也能让孩子多睡一会儿。所以方圆一公里范围成了主要选择点。
// 倒序遍历2*len-1次：模拟数组循环（核心！易错点1）