Address issues found in couple.js [Opened by bitHound]

 bitHound discovered 1 Complex Function in [couple.js](https://github.com/rtc-io/rtc-tools/blob/55411ee04ee435a018b3a2df34e579e2dc618c0d/couple.js). For details go to [bitHound](https://www.bithound.io/github/rtc-io/rtc-tools/blob/55411ee04ee435a018b3a2df34e579e2dc618c0d/couple.js). 
