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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def rahukaalam_utc(self, date, latitude, longitude, observer_elevation=0):
 """Calculate ruhakaalam times in the UTC timezone. :param date: Date to calculate for. :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 Rahukaalam for :type observer_elevation: int :return: Tuple containing the start and end times for Rahukaalam. :rtype: tuple """


        if date is None:
            date = datetime.date.today()

        sunrise = self.sunrise_utc(date, latitude, longitude, observer_elevation)
        sunset = self.sunset_utc(date, latitude, longitude, observer_elevation)

        octant_duration = datetime.timedelta(seconds=(sunset - sunrise).seconds / 8)

        # Mo,Sa,Fr,We,Th,Tu,Su
        octant_index = [1, 6, 4, 5, 3, 2, 7]

        weekday = date.weekday()
        octant = octant_index[weekday]

        start = sunrise + (octant_duration * octant)
        end = start + octant_duration

        return start, end