定方向：求「下一个」→ 倒序；求「上一个」→ 正序。
The algorithm also visits children in order of distance to the query point. This means it checks the most promising quadrants first, which tends to find a good candidate early and enables aggressive pruning of the remaining quadrants. Without this ordering, the algorithm would still produce the correct result, but it would prune fewer nodes.
，详情可参考搜狗输入法2026
대구 간 한동훈 “죽이되든 밥이되든 나설것”。关于这个话题，Line官方版本下载提供了深入分析
.pipeThrough(parse) // buffers filling...