If you know the irc protocol you should know that a whois output is made of multiple data, which are sent over via what's called raw, so for each piece of infos, you have to assign the value to a variable, there's no such things as getting the output from a function because the data has to be sent from the server, mIRC doesn't store that, there's no easy way to do that, you would have the same issue with python.
