anchor.diff:  code_change(_OldVsn, Data, _Extra) ->
       {ok, Data}.
   
  +do_send(_Out, _SocketFd, _Filename, _Offset, Count) when Count =< 0 ->
  +    {ok, 0};
   do_send(Out, SocketFd, Filename, Offset, Count) ->
       Call = list_to_binary([<<Offset:64, Count:64, SocketFd:32>>,
                              Filename, <<0:8>>]),
  
positive.code: 
  -include_lib("kernel/include/file.hrl").
  
  start_link() ->
      gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
  
  
negative.code: enabled() ->
      true.
  
  send(Out, Filename, Offset, Count) ->
      Count1 = case Count of
                   all ->
                       case file:read_file_info(Filename) of
                           {ok, #file_info{size = Size}} ->
                               Size - Offset;
                           Error ->
                               Error
                       end;
                   Count when is_integer(Count) ->
                       Count;
                   _ ->
                       {error, badarg}
               end,
      case Count1 of
          {error, _}=Error2 ->
  