code: def next_trigger_frequency(self, utc_now=None):
          
          if utc_now is None:
              utc_now = datetime.utcnow()
  
          def wind_days(start_date):
              while True:
                  if self.day_of_week == EVERY_DAY or start_date.weekday() == int(self.day_of_week):
                      return start_date.replace(hour=self.time_of_day.hour, minute=self.time_of_day.minute)
                  else:
                      start_date += timedelta(days=1)
  
          if utc_now.time() > self.time_of_day.time():
              return wind_days(utc_now + timedelta(days=1))
          else:
              return wind_days(utc_now)
docs: :param utc_now: optional parameter to be used by Unit Tests as a definition of "now"
              :return: datetime instance presenting next trigger time of the event