How would I go about making a topic append command, so it would just add something on to the current topic like:

* Now talking in #chat
* Topic is 'Come on in and chat!

<Bob> !append | No Flooding, or use of foul language.

* Bot changes topic to 'Come on in and chat! | No flooding, or use of foul language.'

on *:text:!append *:#chat:{
topic $chan $chan($chan).topic $2-
}

Thanks