;; exmple of FSM
;; vending machine
;; - gum :: 15 cents
;; - mints :: 20 cents
;; any combination of
;; DIME - 10c
;; NICKEL - 5c
;; if enough money is in, press of either button would get you the product and change
;; pressing coin return at any time will return amount equal to being put in so far

;;; and the exercise is to use macro to compile FSM with functions for states, from defstate & defarc structures
;; that seems cool