(define-source-transform sb!bignum:%multiply-and-add (x y carry &optional (extra 0))
#+nil ;; This would be greate if it worked, but it doesn't.
(if (eql extra 0)
(define-source-transform sb!bignum:%multiply-and-add (x y carry &optional (extra 0))
#+nil ;; This would be greate if it worked, but it doesn't.
(if (eql extra 0)