anchor.diff:  
   %% API
   -export([start_link/0,
  +         stop/0,
            enable_plugin/1,
            enable_plugin/2,
            enable_module_plugin/3,
  
positive.code: %%                                   {stop, Reason, State}
  %% @end
  %%--------------------------------------------------------------------
  handle_call(Call, _From, #state{ready=true} = State) ->
      handle_plugin_call(Call, State);
  handle_call(Call, From, #state{defered_calls=DeferedCalls} = State) ->
  
negative.code: start_link() ->
      gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
  
  stop() ->
      %% only call after all application that call INTO a
      %% plugin are stopped...
      gen_server:call(?MODULE, stop, infinity).
  
  -spec enable_plugin(atom()) -> ok | {error, _}.
  enable_plugin(Plugin) ->
      enable_plugin(Plugin, auto).
  