Laravel-echo-server: how to listen to user leaving a channel

I've been fiddling a lot lately with Laravel Echo and Laravel Echo Server, a socket.io server implementation for Laravel Echo.

There's not much on the web, and I'm probably missing some point..

I can see from the cli of laravel-echo-server when a user joins or leaves a channel (presence channel in my case). I have a Laravel Event that performs some DB operations that I want to fire when a user leaves a presence channel. How can I achieve this?

Thanks

via Edo San