preparing for const, final, and invariant

[Manuel König]

I second this.

Doing it this way 'in' also keeps its expressive character of saying 
"Hey, I am only the input and not that bunch of scope const final!", 
which especially makes sense when compared to 'out' in terms of data 
flow. And dismissing all of 'scope const final' just requires you to 
declare your params as 'in', which will rarely be the case.