'English ordinal suffix for the day of the month, 2 characters; i.e. \'st\', \'nd\', \'rd\' or \'th\''

def S(self):

    if (self.data.day in (11, 12, 13)):
        return 'th'
    last = (self.data.day % 10)
    if (last == 1):
        return 'st'
    if (last == 2):
        return 'nd'
    if (last == 3):
        return 'rd'
    return 'th'
