class Student(object):
    def __init__(self, name, score):
        self.name = name
        self.score = score
    def __str__(self):
        return '(%s: %s)' % (self.name, self.score)
    __repr__ = __str__

    def __cmp__(self, s):
        if self.name < s.name:
            return -1
        elif self.name > s.name:
            return 1
        else:
            return 0
 L = [Student('Tim', 99), Student('Bob', 88), 100, 'Hello']

K=map(lambda L:L if isinstance(L,Student),L)   最后这个语句为什么错了啊？if 不能和INSTANCE连用吗