Description
A utility method to prefix the value with the prefix setting for phpredis.
用于给VALUE加入前缀
Parameters
value string. The value you wish to prefix
Return value
If a prefix is set up, the value now prefixed. If there is no prefix, the value will be returned unchanged.
如果设置了前缀，值为当前前缀。如果没有前缀，返回值不变。
Examples
$redis->setOpt(Redis::OPT_PREFIX, 'my-prefix:');
$redis->_prefix('my-value'); // Will return 'my-prefix:my-value'
