1 (define (equal? p1 p2)
2   (cond ((and (null? p1) (null? p2)) #t)
3 	((or (null? p1) (null? p2)) #f)
4 	((and (pair? p1) (pair? p2))
5 	 (and (equal? (car p1) (car p2))
6 	      (equal? (cdr p1) (cdr p2))))
7 	((or (pair? p1) (pair? p2)) #f)
8 	(else (eq? p1 p2))))
9 (car ''abracadabra)