ex2.30.scm

(define (scale-tree tree factor)
  (map (lambda (sub-tree)
         (if (pair? sub-tree)
             (scale-tree sub-tree factor)
             (* sub-tree factor)))
       tree))


(define (square-tree tree)
    (map (lambda (sub-tree)
         (if (pair? sub-tree)
             (square-tree sub-tree)
             (* sub-tree sub-tree)))
       tree))

(square-tree
 (list 1
       (list 2 (list 3 4) 5)
       (list 6 7)))