CI Redis cache driver

Hi, 

In CI version 3.x we have Redis support.
Official documentation for 'more information' points to https://github.com/phpredis/phpredis
But if I user for example:

Code:

$this->cache->redis->hSet('h', 'key1', 'hello');
Error: 

Type:        BadMethodCallException
Message:     No such method: hSet()

Also in system\libraries\Cache\drivers\Cache_redis.php 
We have ony save, get, delete, increment, decrement, clean, cache_info, get_metadata

How I can use this?
What to do?

Thanks