anchor.diff:        fun({{in, T}, LocalPrefix}) ->
                 case vmq_topic:match(Topic, T) of
                     true ->
  -                      ok = PublishFun(lists:flatten([LocalPrefix, Topic]), Payload);
  +                      ok = PublishFun(routing_key(LocalPrefix, Topic), Payload);
                     false ->
                         ok
                 end;
  
positive.code:             gen_emqtt:subscribe(Pid, TTopic, QoS),
              ok = SubscribeFun(TTopic),
              bridge_subscribe(Pid, Rest, SubscribeFun, [{{in, TTopic},
                                                          list_to_binary(LocalPrefix)},
                                                         {{out, TTopic}, QoS,
                                                          list_to_binary(RemotePrefix)}|Acc]);
          {error, Reason} ->
              error_logger:warning_msg("can't validate bridge topic conf ~p due to ~p",
                                       [BT, Reason]),
  
negative.code:         {ok, TTopic} ->
              ok = SubscribeFun(TTopic),
              bridge_subscribe(Pid, Rest, SubscribeFun, [{{out, TTopic}, QoS,
                                                          validate_prefix(RemotePrefix)}|Acc]);
          {error, Reason} ->
              error_logger:warning_msg("can't validate bridge topic conf ~p due to ~p",
                                       [BT, Reason]),
  