anchor.diff:  leave(Node) ->
       gen_server:call(?MODULE, {leave, Node}, infinity).
   
  +%% @doc Debugging.
  +state() ->
  +    gen_server:call(?MODULE, state, infinity).
  +
   %% @doc Decode state.
   decode(Active) ->
       sets:to_list(Active).
  
positive.code: handle_call({join, {_Name, _, _}=Node}, _From, State) ->
      gen_server:cast(?MODULE, {join, Node}),
      {reply, ok, State};
  
  handle_call({send_message, Name, Message}, _From,
              #state{connections=Connections}=State) ->
  
negative.code:          receive_message/1,
           decode/1]).
  
  %% debug.
  -export([state/0]).
  
  %% gen_server callbacks
  -export([init/1,
           handle_call/3,
  