(define (memoize f)
   (let ((table (make-table 60)))
      (lambda (x)
         (let ((result-deja-obtenu
		(cherche x table)))
            (or result-deja-obtenu
                (let ((result (f x)))
                   (insert! x result table)
                   result))))))

(define fib
   (memoize
    (lambda (n)
       (if (< n 2)
	   n
	  (+ (fib (- n 1))
	     (fib (- n 2)))))))