     var cmd = "import bokeh.io.notebook as ion; ion.destroy_server('" + server_id + "')";
      cell.notebook.kernel.execute(cmd);
    }
  }

  /**
   * Handle when a new output is added
   */
  function handleAddOutput(event, handle) {
    var output_area = handle.output_area;
    var output = handle.output;

    // limit handleAddOutput to display_data with EXEC_MIME_TYPE content only
    if ((output.output_type != "display_data") || (!output.data.hasOwnProperty(EXEC_MIME_TYPE))) {
      return
    }

  