anchor.diff:  
   -module(mem3_sync_event_listener).
   -behavior(couch_event_listener).
  +-behavior(config_listener).
   
   -export([
       start_link/0
  
positive.code:     handle_info/2
  ]).
  
  -include_lib("mem3/include/mem3.hrl").
  
  -record(state, {
      nodes,
      shards,
      users
  }).
  
  start_link() ->
      couch_event_listener:start_link(?MODULE, [], [all_dbs]).
  
  init(_) ->
      State = #state{
          nodes = mem3_sync:nodes_db(),
          shards = mem3_sync:shards_db(),
          users = mem3_sync:users_db()
      },
      {ok, State}.
  
  terminate(_Reason, _State) ->
      ok.
  
negative.code:             lists:member(N, Live)]
      catch error:database_does_not_exist ->
          ok
      end.
  