anchor.diff:  %% @doc Replay trace.
   replay(Type, Message) ->
       gen_server:call({global, ?MODULE}, {replay, Type, Message}, infinity).
  +
  +%% @doc Enable trace.
  +enable() ->
  +    gen_server:call({global, ?MODULE}, enable, infinity).
   
   %% @doc Reset trace.
   reset() ->
  
positive.code:         false ->
              %% This is not a replay, so store the current trace.
              replay_debug("recording trace to file.", []),
              #state{trace=[], blocked_processes=[], identifier=undefined};
          _ ->
              %% Mark that we are in replay mode.
              partisan_config:set(replaying, true),
  
negative.code: 
      case PreviousTrace of 
          [{NextType, NextMessage} | _] ->
              replay_debug("waiting for message ~p: ~p ", [NextType, NextMessage]),
  
              CanDeliver = case {NextType, NextMessage} of 
                  {Type, Message} ->
                      replay_debug("=> YES!", []),
  