def callback(func):    def inner(obj, *args, **kwargs):        res = func(obj, *args, **kwargs)        if kwargs.get('callback'):            callback = kwargs.get('callback')            success = getattr(obj, callback)            success()        return success()    return innerclass BaseHandler(object):    @callback    def reverse_str(self, str, *args, **kwargs):        return str[::-1]    def success(self):        return 'success'res= BaseHandler().reverse_str('abcdefgh', callback='success')print(res)