anchor.diff:  
   -export([start_link/0,
            link/0,
  -         add_subscription/2,
            add_subscription/3,
  -         del_subscription/2,
            del_subscription/3,
            get_subscriptions/1]).
   
  
positive.code:     link(whereis(?MODULE)),
      put('$ancestors', [?MODULE | get('$ancestors')]).
  
  add_subscription(Queue, DeliveryProc) ->
      add_subscription(Queue, undefined, DeliveryProc).
  
  add_subscription(Queue, Id, DeliveryProc) ->
      case ets:match_object(?MODULE, {self(), Queue, Id, DeliveryProc}) of
          [] ->
  
negative.code:         [_] ->
              false
      end.
  
  del_subscription(Queue, Id, DeliveryProc) ->
      case ets:match_object(?MODULE, {self(), Queue, Id, DeliveryProc}) of
  