Wishlist proposal, documenting fn arg as in or out or mod

[Adam D Ruppe]

On Tuesday, 20 June 2023 at 15:01:17 UTC, Cecil Ward wrote:
> So I propose a new keyword either something like modified or 
> mod or rw or input_output. Beauty contest, I don’t care what 
> wins. (Shame inout is already taken.)

Fun fact: the reason `inout` is a keyword in D is that this is 
what it used to be.

Back on the old days, `inout` meant `ref`. But people kept asking 
so it got renamed to ref, and then inout was eventually 
reassigned to the const forwarding thing it is now (which was 
originally gonna be called `return` but never got implemented, 
and now `return` is used to indicate the lifetime of the 
parameter is the same as the return value, lolol)