(define-signature args^ (size secs quiet))
(define-signature bigger^ ((open args^) fname))
(define-signature ui^ (show-mesg display-move))
(define-signature run^ ((open args^) (open ui^)))
(define-signature struct^ ((struct board (size row free))
			   (struct player (num file type))
			   (struct move (num x y time))))
(define-signature top^ (run))