class Student(object):
    def __init__(self,name, gender):
        self.__name = name
        self.__gender = gender

    def set_name(self,name):
        if not isinstance(name,str):
            raise ValueError('name must be an str type')
        else:
            self.__name = name

    def get_name(self):
        return self.__name

    def set_gender(self, gender):
        if gender != 'male' or gender != 'female':
            raise ValueError('gender must be male or female')
        else:
            self.gender = gender

    def get_gender(self):
        return self.__gender