[Away] to [AFK] etc...?

[Triksterism]

What would be the easiest way to replace WoW's <Away> and <Busy> displays with <AFK> and <DND> respectively?

I've seen this done with other UIs (ElvUI, Altz UI) with something like this:

--flags
CHAT_FLAG_AFK = "[AFK] "
CHAT_FLAG_DND = "[DND] "
CHAT_FLAG_GM = "[GM] "

but I prefer RealUI and I would like this simple little thing to work with this UI as well.