anchor.diff:      append_to_file(Filename, Line).
   
   %% @private
  +record_event(Duration) ->
  +    Filename = main_log(),
  +    Timestamp = timestamp(),
  +    Line = get_line(event, Timestamp, Duration),
  +    append_to_file(Filename, Line).
  +
  +%% @private
   record_batch(Start, End, Events) ->
       Filename = main_log(),
       Timestamp = timestamp(),
  
positive.code: -spec batch(term(), term(), number()) -> ok | error().
  batch(Start, End, Events) ->
      gen_server:call(?MODULE, {batch, Start, End, Events}, infinity).
  
  -spec experiment_started() -> ok | error().
  experiment_started() ->
  
negative.code:          experiment_started/0,
           convergence/0,
           batch/3,
           event/1,
           stop/0,
           log_files/0]).
  
  