scheme-interpreter-story/initial-work/t6.scm

(define a ((lambda (b)
	    (lambda (x)
	      (begin (set-box-value! b (+ 1 (box-value b)))
		     (box-value b))))
	   (box 0)))
(define b (begin (print (a #t))
		 (print (a #t))
		 (print (a #t))
		 (print (a #t))
		 (print (a #t))))