/**
  * Calls the current workspace bundle_source method to allow for
  * different implementations of the bundling technique.
  *
  * @param string $filename  The name of the file to be created
  * @param string $source    The path or URL of the resource which is going to
  *                          be bundled
  */
 protected function bundle_source($filename, $source)
 {
     $this->workspace->bundle_source($filename, $source);
 }