def total_duration(self) -> datetime.timedelta:
        """
        Returns a ``datetime.timedelta`` object with the total sum of
        durations. If there is overlap, time will be double-counted, so beware!
        """
        total = datetime.timedelta()
        for interval in self.intervals:
            total += interval.duration()
        return total
Returns a ``datetime.timedelta`` object with the total sum of
        durations. If there is overlap, time will be double-counted, so beware!