Synchronous fast paths matter
Change watching: wait_for_change waits for any transition regardless of value, handy for logging or reacting to state churn.
，更多细节参见雷速体育
One annotator sums it up:
新春伊始，记者走进天津市、重庆市和广东省广州市，循着入境游客的旅程，看消费选择、听真实感受，见证中国开放的大门越开越大。