title: How to reset Observable.interval
body: <p>How can I construct an observable which emits at some predetermined interval, but also can be made to emit when a second observable emits, at which point the interval will be "reset" to start emitting again at the original interval starting from the point of the second ping?</p>
  
  <p>For example, let's say the interval is 10 minutes. The observable would emit at 10, 20, 30, etc. But let's say the second observable at emits at time 15. Then the overall observable should ping at 10, 15, 25, 35, etc.</p>