(defcc <?bscs>
   <?s> <bs> <cs>;)

(defcc <?s>
   a <?s>;
   a;
   b <?s>;
   b;)

(defcc <bs>
  b <bs>;
  b;)

(defcc <cs>
  c <cs>;
  c;)

(compile (fn <?bscs>) [a a a b b b c c c])