> as soon as you add a new yield point, you invalidate your safety assumptions. While true, locks aren't free from this problem. They have the inverse. If some

> as soon as you add a new yield point, you invalidate your safety assumptions. While true, locks aren't free from this problem. They have the inverse. If someone adds code that accesses a data structure that should be protected by a lock and they forget to add the lock, you also lose all of your safety assumptions.