Ex-3.25

(define (make-table) (list '*table*))

(define (insert! value table . keys)
  (if (not (null? keys))
      (let ((record (assoc (car keys) (cdr table))))
        (if (not record)
            (begin
              (set! record (cons (car keys) nil))
              (set-cdr! table (cons record (cdr table)))))
        (if (null? (cdr keys))
            (set-cdr! record value)
            (apply insert!
                   (cons value
                         (cons record (cdr keys))))))))

(define (lookup table . keys)
  (if (null? keys) #f
      (let ((record (assoc (car keys) (cdr table))))
        (if record
            (if (null? (cdr keys))
                (cdr record)
                (apply lookup (cons record (cdr keys))))
            #f))))