Well it’s basically just a nonce/state. Just echo it back.
In tmi.js, Promises are returned for most things including commands and messages. It’s typically a little more than a guess that a thing worked based on events so that it can resolve or reject. Being able to know that there was success or failure would improve the quality. My bot is built around Promises so just having a guess isn’t really good enough if there’s some sequence, logging, statistics, error detection, etc. that needs to happen.