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

    def set_gender(self, gender):
    	if gender in ('male', 'female'):
    		self.__gender = gender
    	else:
    		print('No such gender!')

    def get_gender(self):
    	return self.__gender


# 测试:
bart = Student('Bart', 'male')
print(bart.get_gender())

bart.set_gender('fmale')

bart.set_gender('female')
print(bart.get_gender())