throws Throwable
throws IOException
  public static Value dump_stack()    throws Throwable  {    Exception e = new Exception("Stack trace");    e.fillInStackTrace();    com.caucho.vfs.WriteStream out = com.caucho.vfs.Vfs.openWrite("stderr:");    try {      ScriptStackTrace.printStackTrace(e, out.getPrintWriter());    } finally {      out.close();    }    return NullValue.NULL;  }