anchor.diff:      cowboy_req:req().
   download_single_regular_file(SessionId, #file_attr{
       guid = FileGuid,
  -    name = FileName,
       size = FileSize
   }, FileName, OnSuccessCallback, Req0) ->
       case http_parser:parse_range_header(Req0, FileSize) of
  
positive.code:         http_streamer:send_data_chunk(NextPartHead, Req1),
          http_streamer:stream_bytes_range(StreamingCtx, Range, Req1)
      end, Ranges),
      
      {Boundary, Req1}.
  
  
  
negative.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, [
  