(define naravna (letrec([f (lambda(x) (cons x (lambda() (f(+ x 1)))))])
                  (f 1)))

(define skoki (letrec([f (lambda(x) (cons x (lambda() (f(cond [(= x 0) 1] [(= x 1) 2] [(= x 2) 0]))  )))])
                   (f 1)))


;samostojno
(define (preskocni tok skoki)
  (letrec([f (lambda(x y) (cons (car x) (lambda() (f (letrec(
                                                             [l (lambda(a b) (cond
                                                                               [(> b 0) (l ((cdr a)) (- b 1)) ]
                                                                               [else a]))])
                                                       (l x (car y)))  ((cdr skoki)) ))))])
    (f tok skoki)))

;priprava na kolokvij
(define (preskocni tok skoki)
  (letrec([f (lambda(t x) (if(= x 0) (car t) (f ((cdr t)) (- x 1)) ))])
    cons (car tok) (lambda() (preskocni (f((cdr tok)) (car skoki)) ((cdr skoki)) )))
  )