start
   def tree(s, n) {
      start
      if (n <= 0) {
         start
            forward s;
            forward 0-s;
         end
      }
      else {
         start
            forward (7/10) * s;
            turn 0-30;
            call tree(2*s/3, n-1);
            turn 60;
            call tree(2*s/3, n-1);
            turn 0-30;
            forward (0-7/10) * s;
         end
      }
      end
   }
   turn 90;
   forward 0-400;
   down;
   call tree(400, 11);
end