code: def twilight_utc(self, direction, date, latitude, longitude, observer_elevation=0):
          
  
          if date is None:
              date = datetime.date.today()
  
          start = self.time_at_elevation_utc(-6, direction, date, latitude, longitude, observer_elevation)
          if direction == SUN_RISING:
              end = self.sunrise_utc(date, latitude, longitude)
          else:
              end = self.sunset_utc(date, latitude, longitude)
  
          if direction == SUN_RISING:
              return start, end
          else:
              return end, start
docs: Returns the start and end times of Twilight in the UTC timezone when
          the sun is traversing in the specified direction.
  
          This method defines twilight as being between the time
          when the sun is at -6 degrees and sunrise/sunset.
  
          :param direction:  Determines whether the time is for the sun rising or setting.
                             Use ``astral.SUN_RISING`` or ``astral.SUN_SETTING``.
          :type direction:   int
          :param date: The date for which to calculate the times.
          :type date: :class:`datetime.date`
          :param latitude:   Latitude - Northern latitudes should be positive
          :type latitude:    float
          :param longitude:  Longitude - Eastern longitudes should be positive
          :type longitude:   float
          :param observer_elevation:  Elevation in metres to calculate twilight for
          :type observer_elevation:   int
  
          :return: A tuple of the UTC date and time at which twilight starts and ends.
          :rtype: (:class:`~datetime.datetime`, :class:`~datetime.datetime`)