3 (define (lookup given-key set-of-records)
4 (if (null? set-of-records)
6 (let* ((e (entry set-of-records))
8 (cond ((equal? given-key k) e)
9 ((< k given-key) (lookup given-key (left-branch set-of-records)))
10 ((> k given-key) (lookup given-key (right-branch set-of-records)))))))