; (cadar-of <procedure of n arguments>)
(define-syntax cadar-of
 (ir-macro-transformer
  (lambda (expr inject compare)
   (assert (pair? expr))
   (let* ((proc (second expr))
	 )
   ;(list 'quote
    `(lambda x
     (->* x
      (,proc)
      (extract-cadar)))
   ;)
  ))))

(define (meta-meta/validUntil . x)
  (->* x
       ((sxpath '(validUntil)))
       (extract-cadar)))

(define meta-meta/validUntil
  (cadar-of
    (sxpath '(validUntil))))