How to reference @event handler?

[essenciary]

@hhaensel I've added here a demo of the Tables server side API.
https://github.com/GenieFramework/StippleUI.jl/blob/master/demos/tables/app.jl

However, as you can see, both @event :request and @onchange filter have the same logic, and @onchange filter should invoke the @event :request handler.

However, I don't understand where the handler is stored and how can I fetch it. Clearly it's somewhere since it's being called from the client side, but I can't figure it out. Can you help please?