btree_0.rkt

(define t-empty #f)
(define t-value car)
(define t-left cadr)
(define t-right caddr)

(define (t-node value l-node r-node)
  (list value l-node r-node))

(define (t-empty? node)
  (equal? node t-empty))

#||
(define (t-empty? node)
(if (equal? node t-empty)
#t
(and (equal? (t-left node) t-empty)
(equal? (t-right node) t-empty))))
||#