anchor.diff:  
   handle_call(nodes_wanted, _From, State) ->
       {reply, do_nodes_wanted(), State};
  -
  -handle_call(nodes_wanted_updated, _From, State) ->
  -    {reply, do_nodes_wanted_updated(do_nodes_wanted()), State};
   
   handle_call(Msg, _From, State) ->
       error_logger:info_msg("Unhandled ~p call: ~p~n", [?MODULE, Msg]),
  
positive.code: % keys have changed.
  
  nodes_wanted_updated() ->
      gen_server:call(?MODULE, nodes_wanted_updated).
  
  %% gen_server implementation
  
  
negative.code:     timer:cancel(State#state.timer),
      ok.
  code_change(_OldVsn, State, _) -> {ok, State}.
  
  handle_cast(nodes_wanted_updated, State) ->
      do_nodes_wanted_updated(do_nodes_wanted()),
      {noreply, State};
  
  handle_cast(_Msg, State)       -> {noreply, State}.
  
  % Read from ns_config nodes_wanted, and add ourselves to the
  