4 и 5 / Exam

from Date import Date
from datetime import date

class DisciplineException(Exception):
    pass

class Exam(Date):
    discipline = "unknown"
    professor = "unknown"

    def __init__(self, d, m, y, n=None, p=None):
        try:
            if n not in ("C#", "Python", "Pascal", "C++", "SQL"):
                raise DisciplineException("Введен несуществующий предмет")
        except DisciplineException as e:
            print(e)
        if p is not None:
            self.professor = p
        else:
            self.professor = "unknown"
        Date.__init__(self, d, m, y)

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

    def __str__(self):
        return "Преподаватель: {},предмет: {},дата экзамена: {}".format(self.professor ,self.discipline, date(self.year, self.month, self.day))