class Chain(object):
    def __init__(self, path=''):
        self._path = path
    def __getattr__(self, path):
        #%s%s将字符串相互联系在一起
        return Chain('%s/%s' % (self._path, path))
    def __str__(self):
        return self._path
    def users(self,value):
        return Chain("%s%s"%(self._path,value))
    __repr__ = __str__

print(Chain().users('michael').repos)

要点： Chain('%s/%s' % (self._path, path)) 一直让Chain的path向后延伸