("format_odd": string "odd %d\n\000")
("format_even": string "even %d\n\000")

(function "force_spill" (a:int) 0)

(function "is_even" (b:int)
  (catch (exit even b)
   with (odd v)
     (if (== v 0) 0
         (seq
           (extcall "printf_int" "format_odd" v unit)
           (let v2 (- v 1)
             (app "force_spill" 0 int)
             (exit even v2))))
   and (even v)
     (if (== v 0) 1
         (seq
           (extcall "printf_int" "format_even" v unit)
           (exit odd (- v 1))))))