// returns (timer, estimated firing time) or null
static Pair<O, Long> nextFiringTimerInVM() {
  Collection timers = allTimersInVM();
  long time = now();
  new Lowest best;
  for (O timer : timers) pcall {
    long t = timer_nextFireTime(timer);
    if (t != 0)
      best.put(timer, t);
  }
  ret best.has() ? pair(best!, toLong(best.bestScore())) : null;
}