docs: def havdalah(self):
          """Return the time for havdalah, or None if not applicable.
  
          If havdalah_offset is 0, uses the time for three_stars. Otherwise,
          adds the offset to the time of sunset and uses that.
          If it's currently a multi-day YomTov, and the end of the stretch is
          after today, the havdalah value is defined to be None (to avoid
          misleading the user that melacha is permitted).
          """
          today = HDate(gdate=self.date, diaspora=self.location.diaspora)
          tomorrow = HDate(gdate=self.date + dt.timedelta(days=1),
                           diaspora=self.location.diaspora)
  
          # If today is Yom Tov or Shabbat, and tomorrow is Yom Tov or Shabbat,
          # then there is no havdalah value for today. Technically, there is
          # havdalah mikodesh l'kodesh, but that is represented in the
          # candle_lighting value to avoid misuse of the havdalah API.
          if today.is_shabbat or today.is_yom_tov:
              if tomorrow.is_shabbat or tomorrow.is_yom_tov:
                  return None
              return self._havdalah_datetime
          return None