1(define rec 2 (lambda (n stop) 3 (display n) (newline) 4 (if (= n 0) (stop 0) 5 (begin 6 (rec (- n 1) stop) 7 (display n) (newline))))) 8(rec 6 (lambda (x) '())) 9(call-with-current-continuation 10 (lambda (t) (rec 6 t))) 11 12