class Person(object):

? ? __slots__ = ('name', 'gender')

? ? def __init__(self, name, gender):

? ? ? ? self.name = name

? ? ? ? self.gender = gender

class Student(Person):

? ? __slots__ = ('score',)

? ? def __init__(self,name, gender,score):

? ? ? ? super(Student,self).__init__(name, gender)

? ? ? ? self.__score=score

? ??

? ? @property

? ? def score(self):

? ? ? ? return self.__score

s = Student('Bob', 'male', 59)

s.name = 'Tim'

s.score = 99

print s.score