anchor.diff:  -record(state, {
             nodes :: [node()],
             we_were_shunned = false :: boolean(),
  -          node_renaming_txt_mref :: undefined | reference()
  +          node_renaming_txn_mref :: undefined | reference()
            }).
   
   -include_lib("eunit/include/eunit.hrl").
  
positive.code:     ?log_warning("Unhandled ~p call: ~p", [?MODULE, Msg]),
      {reply, error, State}.
  
  handle_info({'DOWN', MRef, _, _, _}, #state{node_renaming_txt_mref = MRef} = State) ->
      self() ! notify_clients,
      {noreply, State#state{node_renaming_txt_mref = undefined}};
  handle_info({nodeup, Node}, State) ->
      ?user_log(?NODE_UP, "Node ~p saw that node ~p came up.",
                [node(), Node]),
  
negative.code: 
  handle_call({register_node_renaming_txn, Pid}, _From, State) ->
      case State of
          #state{node_renaming_txn_mref = undefined} ->
              MRef = erlang:monitor(process, Pid),
              NewState = State#state{node_renaming_txn_mref = MRef},
              {reply, ok, NewState};
          _ ->
              {reply, already_doing_renaming, State}
  