1 (define (count-leaves x)
2   (cond ((null? x) 0)
3 	((not (pair? x)) 1)
4 	(else (+ (count-leaves (car x))
5 		 (count-leaves (cdr x))))))
6 
7 (list 1 (list 2 (list 3 4)))
8 '(1 (2 (3 4)))