anchor.diff:          {ok, TTopic} ->
               ok = SubscribeFun(TTopic),
               bridge_subscribe(Pid, Rest, SubscribeFun, [{{out, TTopic}, QoS,
  -                                                        list_to_binary(RemotePrefix)}|Acc]);
  +                                                        validate_prefix(RemotePrefix)}|Acc]);
           {error, Reason} ->
               error_logger:warning_msg("can't validate bridge topic conf ~p due to ~p",
                                        [BT, Reason]),
  
positive.code:     bridge_unsubscribe(Pid, Rest, UnsubscribeFun);
  bridge_unsubscribe(_, [], _) ->
      ok.
  
  client_opts(tcp, Host, Port, Opts) ->
      OOpts =
  
negative.code:             gen_emqtt:subscribe(Pid, TTopic, QoS),
              ok = SubscribeFun(TTopic),
              bridge_subscribe(Pid, Rest, SubscribeFun, [{{in, TTopic},
                                                          validate_prefix(LocalPrefix)},
                                                         {{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]),
  