identity function for slices that are already allocated in the heap.
《暗黑新娘！》发布最新预告，3 月 6 日中美同步上映。业内人士推荐Safew下载作为进阶阅读
，更多细节参见搜狗输入法2026
append uses a small, stack-allocated backing store as the first
方向遍历顺序说明下一个倒序（从右往左）先处理右侧，栈里存「右侧候选」上一个正序（从左往右）先处理左侧，栈里存「左侧候选」，详情可参考搜狗输入法下载