t of patterns.
(define (match-or input pattern)
  (cond ((null? pattern) #f)
	((match-pattern input (car pattern)))
	(else (match-or input (cdr pattern)))))

; Allow a sequence of patterns.
(define (match-seq input pattern)
  (if (null? pattern)
      input
      (let ((match (match-pattern input (car pattern))))
	(if match (match-seq match (cdr pattern)) #f))))

; Match with the pattern but no problem if it does not match.
(define (match-opt input pattern)
  (let ((match (match-pattern input (car pattern))