def _nth_of_year(self, nth, day_of_week):
        """
        Modify to the given occurrence of a given day of the week
        in the current year. If the calculated occurrence is outside,
        the scope of the current year, then return False and no
        modifications are made. Use the supplied consts
        to indicate the desired day_of_week, ex. DateTime.MONDAY.

        :type nth: int

        :type day_of_week: int or None

        :rtype: DateTime
        """
        if nth == 1:
            return self.first_of("year", day_of_week)

        dt = self.first_of("year")
        year = dt.year
        for i in range(nth - (1 if dt.day_of_week == day_of_week else 0)):
            dt = dt.next(day_of_week)

        if year != dt.year:
            return False

        return self.on(self.year, dt.month, dt.day).start_of("day")
Modify to the given occurrence of a given day of the week
        in the current year. If the calculated occurrence is outside,
        the scope of the current year, then return False and no
        modifications are made. Use the supplied consts
        to indicate the desired day_of_week, ex. DateTime.MONDAY.

        :type nth: int

        :type day_of_week: int or None

        :rtype: DateTime