// 从右找第一个小于pivot的
What I found is that written evidence for knocking on wood (and for the history of gesture as a whole) is remarkably sparse. In the Penguin Guide to Superstitions, folklorist Steve Roud offers a skeptical take on the provenance of knocking on wood due to the near total absence of written records about it:
。关于这个话题，搜狗输入法2026提供了深入分析
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drop-oldest: Drops the oldest buffered data to make room. Useful for live feeds where stale data loses value.