color E = with e;

  globref to_prc = IO.std_out;
  globref from_prc = std_in;

  (* change path to fit your filesystem *)
  fun start_process ()
     = let
        val (x,y) = execute_in_env("<specify full path>/sub_process.tcl",[],
            ["DISPLAY=<specify display host>:0.0"]);
       in
        to_prc := y;
        from_prc := x
       end;

  fun send (n:int)
     = (IO.output(!to_prc,(makestring n)^"\n");
        IO.flush_out (!to_prc));

  exception Comm_Err;
  fun check_response ()
     = case input (!from_prc,2)
         of "1\n" => ()
          | _ => raise Comm_Err;