code: def markDownloaded(self, media):
          
          url = '/sync/%s/item/%s/downloaded' % (self.clientIdentifier, media.ratingKey)
          media._server.query(url, method=requests.put)
docs: Mark the file as downloaded (by the nature of Plex it will be marked as downloaded within
              any SyncItem where it presented).
  
              Parameters:
                  media (base.Playable): the media to be marked as downloaded.