def daytime(date: datetime.date,
                daybreak: datetime.time = datetime.time(NORMAL_DAY_START_H),
                nightfall: datetime.time = datetime.time(NORMAL_DAY_END_H)) \
            -> "Interval":
        """
        Returns an :class:`Interval` representing daytime on the date given.
        """
        return Interval(
            datetime.datetime.combine(date, daybreak),
            datetime.datetime.combine(date, nightfall),
        )