shop-1shqvt8 is running and serving the market's page. Customers will bookmark its address, so the address must not change.

1. Keep its id in ID.
2. Allocate an Elastic IP, keeping its allocation id in ALLOC, and associate it with the instance.
3. Put the instance's public IP in IP now, after the association, and fetch the page from it.
4. Stop the instance, wait until it is stopped, then start it and wait until it is running.
5. Fetch the page from $IP again, and check the instance's public IP.