class Student(object):

    def __init__(self, name, gender):

        self.__name = name

        self.__gender = gender

    def get_gender(self):

        return self.__gender

    def get_name(self):

        return self.__name

    def set_name(self, name):

        self.__name = name

    def set_gender(self, gender):

        if gender == 'male' or 'female':

            self.__gender = gender

bart = Student('bart', 'male')

bart.set_gender('female')

bart.get_gender()

'female'