* Call a function N times at a given interval, then call a cleanup function
* once. repeat_fn is called once immediately, then (times - 1) times
* asynchronously. If times=1, then cleanup_fn() is also called synchronously.
* Call a function N times at a given interval, then call a cleanup function
* once. repeat_fn is called once immediately, then (times - 1) times
* asynchronously. If times=1, then cleanup_fn() is also called synchronously.