class Student(object):
    def __init__(self, name, gender):
        if gender.lower() in ('male', 'female'):
            self.name = name
            self.__gender = gender
        else:
            raise ValueError('Bad parameter')

    def get_gender(self):
        return self.__gender

    def set_gender(self, gender):
        if gender.lower() in ('male', 'female'):
            self.__gender = gender
        else:
            raise ValueError('Bad parameter')