     }
 
     func observePlaylist(playlist: Playlist) {
-        if let _observer = observer {
-            _observer.dispose()
-        }
+        observer?.dispose()
         observer = playlist.signal.observe { index in
             MainScheduler().schedule {
                 self.loadThumbnail(self.imageViews[index], track: playlist.tracks[index])

    @IBOutlet weak var titleLabel: UILabel!
    @IBOutlet weak var trackThumbScrollView: UIScrollView!

    var imageViews: [UIImageView] = []
    var playlist:   Playlist?
    var delegate:   PlaylistStreamTableViewCellDelegate?
    var observer:   Disposable?

    @IBOutlet weak var trackNumLabel: UILabel!

    }

    deinit {
        observer?.dispose()
    }

    override func setSelected(selected: Bool, animated: Bool) {
