ranacseruet

(defparameter *tree2* '(40 (30 (25 () ()) (35 () ())) (60 (50 () ()) ())))
(defparameter *tree* '(3 (2 (1 () ()) ()) (5 () ())))

;validate if given parameter is a binary tree or not
(defun is-tree(tree)
    (cond 
         ((null tree) NIL)
         ((< (list-length tree) 3) NIL)
         (t)
    )