anchor.diff:  
   %% @private
   %% Write the average to files and return the name of the files.
  -write_to_files(TypeToTimeAndBytes, EvalId, EvalNumber) ->
  -    PlotDir = root_plot_dir() ++ "/"
  -           ++ EvalId ++ "/"
  -           ++ EvalNumber ++ "/",
  +write_to_files(TypeToTimeAndBytes, PlotDir) ->
       filelib:ensure_dir(PlotDir),
   
       lists:foldl(
           fun({Type, List}, InputFiles) ->
  -            %% truncate file
               InputFile = PlotDir ++ Type ++ ".csv",
  -            file:write_file(InputFile, "", [write]),
   
               lists:foreach(
                   fun({Time, Bytes}) ->
                       Line = io_lib:format("~w,~w\n", [Time, Bytes]),
  +                    lager:info("LINE : ~p", [Line]),
                       file:write_file(InputFile, Line, [append])
                   end,
                   List
  
positive.code:             "/usr/bin/gnuplot"
      end,
      Command = Bin ++ " -e \""
                    ++ "outputname='" ++ output_file(PlotDir) ++ "'; "
                    ++ "inputnames='" ++ join_filenames(InputFiles) ++ "'; "
                    ++ "titles='" ++  join_titles(Titles) ++ "'\" " ++ plot_file(),
      os:cmd(Command).
  
negative.code: get_title(broadcast)  -> "Broadcast".
  
  %% @private
  run_gnuplot(InputFiles, Titles, OutputFile) ->
      Bin = case os:getenv("MESOS_TASK_ID", "false") of
          "false" ->
              "gnuplot";
  