Creating a namespace-like organization in a google apps script library

I was looking into building a toolset using google apps script. The problem with this is that as far as I can tell in only allows one level of organization. You can create a Library called Stopwatch and call methods Stopwatch.start() and Stopwatch.stop() which is pretty cool.

What I had in mind though was something more like Utils.Stopwatch().start() and Utils.Timer.start() etc. I think it's certainly possible in javascript, but in order to keep breaking Apps Script autocomplete function it needs to be added in a certain format. Below is example an example of doing it wrong (gives an error) but perhaps saves some time. It's based on this article.

/**
* A stopwatch object.
* @return {Object} The stopwatch methods
*/
function Stopwatch() 
{
  var current;

  /**
  * Stop the stopwatch.
  * @param {Time} time in miliseconds
  */
  function timeInSeconds_(time)
  {
    return time/1000;
  }

  return 
    {
      /**
      * Start the stopwatch.
      */
      start: function() 
      {
        var time = new Date().getTime();
        current = timeInSeconds_(time);
      },

      /**
      * Stop the stopwatch.
      * @return {decimal} time passed since calling 
      *    start (in seconds)
      */
      stop: function() 
      {
        var time = new Date().getTime();
        var difference = timeInSeconds_(time) - this.current;
        return difference.toFixed(3);
      }
    };
}

Thanks