code: @JSFunction
      public void close() throws IOException {
          if (reader != null) {
              reader.close();
              reader = null;
          } else if (writer != null) {
              writer.close();
              writer = null;
          }
      }
docs: Close the file. It may be reopened.
  
  Implements a JavaScript function.
  @exception IOException if an error occurred while accessing the file
  associated with this object