Okay, this seems like a great opportunity to improve our counter again.
When last we visited it, we had a single use counter. But, now we know how to start it up, turn it off, and then turn it back on again. This seems like it might be useful for us.
Your Mission
Use switchMap to switch between an interval timer and NEVER based on the the "Start" and "Stop" buttons.
If you get stuck, you can look here for inspiration.