anchor.diff:          undefined -> undefined
       end,
       proplists:get_value(Key, Options, Default).
  -
  -my_controller_mode(_Peer) ->
  -    active.
  -
  -tell_standby(generation_id, State) ->
  -    {ok, State}.
   
   sync_send(MsgFn, State) ->
       sync_send(MsgFn, [], State).
  
positive.code: handle_call({get_async_subscribe, _Module}, _From, State) ->
      {reply, ok, State};
  handle_call(terminate, _From, State) ->
      {reply, ok, State};
  
  % handle callbacks from of_driver
  handle_call({init, IpAddr, DatapathId, Features, Version, Connection, Opt}, _From, State = #?STATE{datapath_id = DatapathId}) ->
      % switch connected to of_driver.
      % this is the main connection.
      State1 = State#?STATE{
          ipaddr = IpAddr,
          features = Features,
          of_version = Version,
          main_connection = Connection,
          aux_connections = [],
          callback_mod = get_opt(callback_mod, Opt),
          opt = Opt
      },
      {reply, {ok, self()}, State1};
  handle_call({connect, _IpAddr, _DatapathId, _Features, _Version, Connection, AuxId, _Opt}, _From, State = #?STATE{aux_connections = AuxConnections}) ->
      State1 = State#?STATE{aux_connections = [{AuxId, Connection} | AuxConnections]},
      % switch connected to of_driver.
  
negative.code: %% ------------------------------------------------------------------
  
  init([DatapathId]) ->
      {ok, #?STATE{datapath_id = DatapathId}}.
  
  % handle API
  