anchor.diff:           terminate/2,
            code_change/3]).
   
  --record(state, {trace=[]}).
  +-record(state, {trace=[], identifier=undefined}).
   
   %%%===================================================================
   %%% API
  
positive.code:          start_link/1,
           record/4,
           reset/0,
           print/0]).
  
  %% gen_server callbacks
  
negative.code: print() ->
      gen_server:call(?MODULE, print, infinity).
  
  %% @doc Identify trace.
  identify(Identifier) ->
      gen_server:call(?MODULE, {identify, Identifier}, infinity).
  
  %%%===================================================================
  %%% gen_server callbacks
  %%%===================================================================
  