def _last_of_quarter(self, day_of_week=None):
        """
        Modify to the last occurrence of a given day of the week
        in the current quarter. If no day_of_week is provided,
        modify to the last day of the quarter. Use the supplied consts
        to indicate the desired day_of_week, ex. DateTime.MONDAY.

        :type day_of_week: int or None

        :rtype: DateTime
        """
        return self.on(self.year, self.quarter * 3, 1).last_of("month", day_of_week)
def _last_of_quarter ( self , day_of_week = None ) : return self . on ( self . year , self . quarter * 3 , 1 ) . last_of ( "month" , day_of_week )
Modify to the last occurrence of a given day of the week
        in the current quarter. If no day_of_week is provided,
        modify to the last day of the quarter. Use the supplied consts
        to indicate the desired day_of_week, ex. DateTime.MONDAY.

        :type day_of_week: int or None

        :rtype: DateTime