anchor.diff:          {json_req, null},
           Db
       ),
  -    ChangesFeedFun({fun ?MODULE:changes_reader_cb/2, {Server, DbName}}).
  -
  -changes_reader_cb({change, Change}, {Server, DbName}) ->
  +    ChangesFeedFun({fun ?MODULE:changes_reader_cb/3, {Server, DbName}}).
  +
  +changes_reader_cb({change, Change}, _, {Server, DbName}) ->
       case has_valid_rep_id(Change) of
           true ->
               Msg = {rep_db_update, DbName, Change},
  
positive.code: -export([code_change/3, terminate/2]).
  
  % changes callbacks
  -export([changes_reader/3, changes_reader_cb/2]).
  
  % config_listener callback
  -export([handle_config_change/5]).
  
negative.code:             ok
      end,
      {ok, {Server, DbName}};
  changes_reader_cb({stop, EndSeq, _Pending}, _, {Server, DbName}) ->
      Msg = {rep_db_checkpoint, DbName, EndSeq},
      ok = gen_server:call(Server, Msg, infinity),
      {ok, {Server, DbName}};
  changes_reader_cb(_, _, Acc) ->
      {ok, Acc}.
  
  has_valid_rep_id({Change}) ->
  