anchor.diff:      update_notifier
   }).
   
  +-record(job, {name, node, count=nil, pid=nil}).
  +
   start_link() ->
       gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
   
  
positive.code: push(Name, #shard{node=Node}) ->
      push(Name, Node);
  push(Name, Node) ->
      gen_server:cast(?MODULE, {push, Name, Node}).
  
  remove_node(Node) ->
      gen_server:cast(?MODULE, {remove_node, Node}).
  
negative.code:         twig:log(debug, "adding ~s -> ~p to mem3_sync queue", [DbName, Node]),
          State#state{
              dict = dict:store({DbName,Node}, ok, D),
              waiting = Waiting ++ [Job]
          }
      end.
  
  