anchor.diff:        HttpHeaders.LAST_MODIFIED: formatHttpDate(fileStat.changed)
       };
   
  -    var contentType = mime.lookupMimeType(file.path);
  +
  +    var contentType;
  +    if(useMagicBytesForContentType) {
  +      List<int> magicBytes = await file.openRead(0,2).single;
  +      contentType = mime.lookupMimeType(file.path, headerBytes: magicBytes);
  +    } else {
  +      contentType = mime.lookupMimeType(file.path);
  +    }
  +
       if (contentType != null) {
         headers[HttpHeaders.CONTENT_TYPE] = contentType;
       }
  
positive.code: /// handler produces a listing of the directory.
  Handler createStaticHandler(String fileSystemPath,
      {bool serveFilesOutsidePath: false, String defaultDocument,
      bool listDirectories: false}) {
    var rootDir = new Directory(fileSystemPath);
    if (!rootDir.existsSync()) {
      throw new ArgumentError('A directory corresponding to fileSystemPath '
  
negative.code:     }
    }
  
    return (Request request) async {
      var segs = [fileSystemPath]..addAll(request.url.pathSegments);
  
      var fsPath = p.joinAll(segs);
  