Yet another use:
#lang scheme
;; Nat -> Pict
;; create a numberline with n dashes
(define (numberline n)
(define h1 20)
(define w1 20)
(define (one i) (cc-superimpose (blank w1 h1) (text (number-
>string i))))
(define mmm (apply hc-append (make-list n (vline w1 h1))))
(define kkk (apply hc-append (build-list n one)))
(define lnn (hline (* w1 n) h1))
(define img (vc-append (cc-superimpose mmm lnn) kkk))
(pin-arrow-line 3.0 img lnn lc-find lnn rc-find))
(numberline 21)
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