+ (when (and keywordp (eq (token-type scanner) #\?))
+ (setf keysp t)
+ (scanner-step scanner)
+ (multiple-value-bind (arg winp consumedp)
+ (parse (list (:min 0) (kw-argument) #\,))
+ (declare (ignore consumedp))
+ (unless winp
+ (return-from argument-list (values arg nil t)))
+ (setf keys arg)
+ (return)))