/**
  * Public URL
  * 
  * If tracking is active, this generates the tracking URL.
  * Otherwise, it's identical to `.url`.
  * 
  * - source: download source for tracking, for example "webplayer", "download" or "feed"
  * - context: (optional) download context for tracking, for example "home"/"episode"/"archive" for player source or feed slug for feed source
  * 
  * @accessor
  */
 public function publicUrl($source, $context = null)
 {
     return $this->file->get_public_file_url($source, $context);
 }