anchor.diff:  
               lager:info("~p: Message after send interposition is: ~p", [node(), Message]),
   
  -            gen_server:reply(From, ok),
  +            case From of 
  +                undefined ->
  +                    ok;
  +                _ ->
  +                    gen_server:reply(From, ok)
  +            end,
   
               {noreply, State#state{vclock=VClock}};
           Message ->
  
positive.code:                           membership_strategy_state=MembershipStrategyState,
                            connections=Connections}};
  
  handle_info(retransmit, #state{connections=Connections}=State) ->
      RetransmitFun = fun({_, {forward_message, Name, Channel, Clock, PartitionKey, ServerRef, Message, _Options}}) ->
          Mynode = partisan_peer_service_manager:mynode(),
          lager:info("~p restranmitting message ~p with clock ~p to ~p", [Mynode, Message, Clock, Name]),
  
          do_send_message(Name,
                          Channel,
                          PartitionKey,
                          {forward_message, ServerRef, Message},
                          Connections)
      end,
      {ok, Outstanding} = partisan_acknowledgement_backend:outstanding(),
      lager:info("~p outstanding messages are: ~p", [node(), Outstanding]),
  
negative.code: 
      case Message of
          undefined ->
              %% Store for reliability, if necessary.
              case proplists:get_value(ack, Options, false) of
                  false ->
                      ok;
                  true ->
                      %% Acknowledgements.
                      RescheduleableMessage = {forward_message, From, Name, Channel, MessageClock, PartitionKey, ServerRef, OriginalMessage, Options},
                      partisan_acknowledgement_backend:store(MessageClock, RescheduleableMessage)
              end,
  
              %% Fire post-interposition functions.
              PostFoldFunUndefined = fun(_Name, PostInterpositionFun, ok) ->
                  PostInterpositionFun({forward_message, Name, OriginalMessage}, {forward_message, Name, Message}),
  