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