phpRedis集群不能使用$ redis-> lsize('...')

I am a chinese student and a new freshman for learn redis. I have completed a project by using the class Redis, but now I will move my project to cluster, so I am using class RedisCluster.

Unfortunately, I suffer a deadly problem, I find that the method of the class can't be used, such as:

$redis=new RedisCluster(
NULL, Array('192.168.1.64:6379', '192.168.1.66:6379', '192.168.1.68:6379'));

echo $redis->lsize('msg_id_list:12');

but the others method are available.

I know the core of the problem , i go to see the document of phpRedis, and I find the correct method is llen() in class RedisCluster, but the correct method is lsize() in class Redis.

think you every one.