func CompareAndSwapMulti(c context.Context, item []*Item) error {
	return set(c, item, nil, pb.MemcacheSetRequest_CAS)
}
func CompareAndSwapMulti(c context.Context, item []*Item) error {
	return set(c, item, nil, pb.MemcacheSetRequest_CAS)
}
// CompareAndSwapMulti is a batch version of CompareAndSwap.
// appengine.MultiError may be returned.