code: def next_run_in(self, utc_now=None):
          
          if utc_now is None:
              utc_now = datetime.utcnow()
  
          if self.is_alive():
              smallest_timedelta = timedelta(days=99, hours=0, minutes=0, seconds=0, microseconds=0, milliseconds=0)
              for event_time in self.timestamps:
                  next_trigger = event_time.next_trigger_frequency(utc_now)
                  if next_trigger - utc_now < smallest_timedelta:
                      smallest_timedelta = next_trigger - utc_now
              return smallest_timedelta
  
          else:
              return None
docs: :param utc_now: optional parameter to be used by Unit Tests as a definition of "now"
              :return: timedelta instance presenting amount of time before the trigger is triggered next time
           or None if the EventClock instance is not running