4 и 5 / DateBirthday

from Date import Date
from datetime import date

class DateBirthday(Date):
    name = "Dasha"

    def __init__(self, d, m, y, n=None):
        if n is not None:
            self.name = n
        else:
            self.name = "unknown"
        Date.__init__(self, d, m, y)

    def display_info(self):
        print(self.__str__())

    def __str__(self):
        return "Имя: {}, дата рождения: {}".format(self.name, date(self.year, self.month, self.day))