Python: How to refer to subclasses in the superclass : I am defining a Python Holiday class and three subclasses: one for fixed date holidays, a second for relative holidays, and a third for floating Monday holidays.  I would like to create a set of constants in the superclass Holiday, but the subclasses obviously do not exist when the parent class is instantiated.  How can I do this?

    class Holiday(object):
        NEW_YEARS = FixedHoliday(1, 1)
        MLK_BIRTHDAY = FloatingMonday(1, 15)
        ...
