anchor.diff:              ok
       end.
   
  --spec annotation(event()) -> {tag(), list(), list()} | {binary(), list(any())} | ignore.
  +-spec annotation(command()) -> {tag(), list(), list()}  | ignore.
   annotation({dist_do, Scenario, Start, End, Nodes, Comment}) ->
       {<<"amoc start">>, "Scenario: ~p. comment: ~p Start: ~p. End: ~p. Nodes: ~p.",
        [Scenario, Comment, Start, End, length(Nodes)]};
  
positive.code:     end,
      {ok, State}.
  
  -spec handle_call(any(), state_annotations()) -> {ok, any(), state_annotations()}.
  handle_call(_Request, State) ->
      Reply = ok,
      {ok, Reply, State}.
  
  -spec handle_info(any(), state_annotations()) -> {ok, state_annotations()}.
  handle_info(_Info, State) ->
      {ok, State}.
  
  
negative.code:          handle_info/2,
           terminate/2,
           code_change/3]).
  
  -record(state, {}).
  
  -type tag() :: binary().
  -type state() :: #state{}.
  -type command() :: {dist_do, amoc_controller:scenario(), non_neg_integer(), non_neg_integer(), amoc_controller:nodes(), any()} |
                     {dist_add, non_neg_integer()} |
                     {dist_remove, non_neg_integer(), list(amoc_controller:option())}.
  
  
  %% ------------------------------------------------------------------
  %% gen_event Function Definitions
  %% ------------------------------------------------------------------
  -spec init([]) -> {ok, state()}.
  init([]) ->
      {ok, #state{}}.
  
  -spec handle_event(command(), state()) ->{ok, state()}.
  handle_event(Event, State) ->
      case annotation(Event) of
          {Tags, Format, Args} ->
  