anchor.diff:  
   -include("types.hrl").
   
  --record(state, {print=true}).
  +-record(state, {print=[time, space, direction, space, packet, nl, frame]}).
   
   %%%===================================================================
   %%% gen_event callbacks
  
positive.code: 
  -behaviour(gen_event).
  %% API
  -export([attach/1]).
  
  %% gen_event callbacks
  -export([init/1, handle_event/2, handle_call/2, 
  
negative.code: %%                   {remove_handler, Reply}
  %% @end
  %%--------------------------------------------------------------------
  handle_call({change_format, Format}, State) ->
      {ok, ok, State#state{print=Format}}.
  
  %%--------------------------------------------------------------------
  %% @private
  