anchor.diff:  
   
   %% @private
  --spec stream_file_internal(undefined | [http_parser:bytes_range()], lfm:handle(), file_meta:size(), 
  +-spec stream_file_internal(undefined | [http_parser:bytes_range()], lfm:handle(), file_meta:size(),
       cowboy_req:req()) -> {binary(), cowboy_req:req()}.
   stream_file_internal(undefined, FileHandle, FileSize, Req) ->
       stream_whole_file(FileHandle, FileSize, Req);
  
positive.code: 
  
  %% @private
  -spec stream_whole_file(lfm:handle(), file_meta:size(), cowboy_req:req()) -> 
      {undefined, cowboy_req:req()}.
  stream_whole_file(FileHandle, FileSize, Req0) -> 
      Req1 = http_streamer:init_stream(
          ?HTTP_200_OK,
          #{?HDR_CONTENT_LENGTH => integer_to_binary(FileSize)},
  
negative.code:     cowboy_req:req().
  download_single_regular_file(SessionId, #file_attr{
      guid = FileGuid,
      size = FileSize
  }, FileName, OnSuccessCallback, Req0) ->
      case http_parser:parse_range_header(Req0, FileSize) of
  