class ERR {
  static public void println(String msg){
    System.err.println(Thread.currentThread().toString() + ": " + msg);
  }
}
class MyThread extends Thread {
  public void run() {
    ERR.println("Hello");
  }
}
class Main {
  public static void main(String[] argv) {
    MyThread aThread = new MyThread();
    ERR.println("this is main");
    aThread.start(); // calls run()
    try {aThread.join();}
    catch (Exception e){ERR.println("Un-joinable");}
    finally {ERR.println("Bye");}
  }
}