Command–query separation principle [re: @mustuse as a function attribute]

[mw]

On Wednesday, 19 October 2022 at 07:41:33 UTC, mw wrote:
>> If anyone is willing to take this and flesh it out further so 
>> that it meets Walter's criteria for applying to functions, 
>> please let me know. It's pretty much guaranteed to be approved.
>
> I wish I have more time, but I just have so many things to do 
> these days.

But if anyone want to work on it, I'd happy to help.