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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 blue_hour(self, direction=SUN_RISING, date=None, local=True, use_elevation=True):
 """Returns the start and end times of the Blue Hour when the sun is traversing in the specified direction. This method uses the definition from PhotoPills i.e. the blue hour is when the sun is between 6 and 4 degrees below the horizon. :param direction: Determines whether the time is for the sun rising or setting. Use ``astral.SUN_RISING`` or ``astral.SUN_SETTING``. Default is rising. :type direction: int :param date: The date for which to calculate the times. If no date is specified then the current date will be used. :type date: :class:`~datetime.date` :param local: True = Times to be returned in location's time zone; False = Times to be returned in UTC. If not specified then the time will be returned in local time :type local: bool :param use_elevation: True = Return times that allow for the location's elevation; False = Return times that don't use elevation. If not specified then times will take elevation into account. :type use_elevation: bool :return: A tuple of the date and time at which the Blue Hour starts and ends. :rtype: (:class:`~datetime.datetime`, :class:`~datetime.datetime`) """


        if local and self.timezone is None:
            raise ValueError("Local time requested but Location has no timezone set.")

        if self.astral is None:
            self.astral = Astral()

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

        elevation = self.elevation if use_elevation else 0
        start, end = self.astral.blue_hour_utc(
            direction, date, self.latitude, self.longitude, elevation
        )

        if local:
            start = start.astimezone(self.tz)
            end = end.astimezone(self.tz)

        return start, end