## getSet ##### *Description* Sets a value and returns the previous entry at that key. 设置一个VALUE 并且返回该KEY当前的VALUE。 ##### *Parameters* *Key*: key *STRING*: value ##### *Return value* A string, the previous value located at this key. ##### *Example* ``` <pre class="calibre9">$redis->set('x', '42'); $exValue = $redis->getSet('x', 'lol'); // return '42', replaces x by 'lol' $newValue = $redis->get('x')' // return 'lol' ```