solution
code
(define (move-tower size from to extra) (cond ((= size 0) #t) (else (move-tower (dec size) from extra to) (print-move from to) (move-tower (dec size) extra to from))))
(define (print-move from to) (begin (newline) (display “move top disk from “) (display from) (display “ to “) (display to))
new features
- begin: sequence of expressions evaluated in order
- displaying has an effect, unlike inc and dec, eg