     /// If it doesn't already exist, generates a thumbnail image of the clip.
     public var thumbnailImage: UIImage? {
         get {
-            guard
-                self._thumbnailImage == nil
-            else {
+            guard self._thumbnailImage == nil else {
                 return self._thumbnailImage
             }
             

    /// Dictionary containing data for re-initialization of the clip.
    public var representationDict: [String:Any]? {
        get {
            if let infoDict = self.infoDict, let url = self.url {
                return [NextLevelClipFilenameKey:url.lastPathComponent,
                        NextLevelClipInfoDictKey:infoDict]
            } else if let url = self.url {

    /// Duration of the clip, otherwise invalid.
    public var duration: CMTime {
        get {
            return self.asset?.duration ?? kCMTimeZero
        }
    }
  
