(define (cddr l) (cdr (cdr l)))
(define (cadar l) (car (cdr (car l))))
+; Return number of items in list
+(define (length l)
+ (define (iter a count)
+ (if (null? a)
+ count
+ (iter (cdr a) (+ count 1))))
+ (iter l 0))
+
; Join two lists together
(define (join l1 l2)
(if (null? l1)