(define (zero? n)
(= n 0))
(define (positive? x)
(> x 0))
(define (negative? x)
(< x 0))
(define (caar p)
(car (car p)))
(define (cadr p)
(car (cdr p)))
(define (cdar p)
(cdr (car p)))
(define (cddr p)
(cdr (cdr p)))
(define (list . args)
args)