anchor.diff:    static Future<List<EpubChapter>> readChapters(
         List<EpubChapterRef> chapterRefs) async {
       List<EpubChapter> result = new List<EpubChapter>();
  -    await chapterRefs.forEach((EpubChapterRef chapterRef) async {
  +    await Future.forEach(chapterRefs, (EpubChapterRef chapterRef) async {
         EpubChapter chapter = new EpubChapter();
   
         chapter.Title = chapterRef.Title;
  
positive.code:       Map<String, EpubTextContentFileRef> textContentFileRefs) async {
      Map<String, EpubTextContentFile> result =
          new Map<String, EpubTextContentFile>();
      await textContentFileRefs
          .forEach((String key, EpubContentFileRef value) async {
        EpubTextContentFile textContentFile = new EpubTextContentFile();
        textContentFile.FileName = value.FileName;
        textContentFile.ContentType = value.ContentType;
  
negative.code:       result.AllFiles[key] = value;
      });
  
      await Future.forEach(contentRef.AllFiles.keys, (key) async {
        if (!result.AllFiles.containsKey(key)) {
          result.AllFiles[key] = await readByteContentFile(contentRef.AllFiles[key]);
        }
      });
  
  