Why is this legal?

[bauss via Digitalmars-d-learn]

On Wednesday, 29 March 2017 at 10:08:02 UTC, abad wrote:
> Related question, it seems that final methods are allowed in 
> interfaces. Obviously you can't implement them anywhere, so is 
> this also on purpose and on what rationale? :)

That is not necessarily true. Final doesn't imply it can't be 
implemented. It implies that it cannot be override.