version vs. static if

[Trass3r]

> If you wanted to use existance of a symbol instead of an enum's value,
> static if(is(typeof())) should do the job.
> Essentially, static if can already do what you're asking for, and is much
> more flexible.

Which again raises the question why we have version at all.
I know it has its very own namespace but you could also let static if have  
access to that and simply make undefined versions evaluate to false.