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: stream_multipart_ranged_body(Ranges, FileHandle, FileSize, Req0) ->
      Boundary = cow_multipart:boundary(),
      ContentType = cowboy_req:resp_header(?HDR_CONTENT_TYPE, Req0),
      
      Req1 = http_streamer:init_stream(
          ?HTTP_206_PARTIAL_CONTENT,
          #{?HDR_CONTENT_TYPE => <<"multipart/byteranges; boundary=", Boundary/binary>>},
          Req0
      ),
      
      StreamingCtx = http_streamer:build_ctx(FileHandle, FileSize),
      lists:foreach(fun(Range) ->
          NextPartHead = cow_multipart:first_part(Boundary, [
  
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
  