anchor.diff:      throw({bad_request, "`doc_ids` filter parameter is not a list."}).
   
   filter_designdoc(Style) ->
  -    fun(#doc_info{id=DocId, revs=Revs}) ->
  +    fun(_Db, #doc_info{id=DocId, revs=Revs}) ->
               case DocId of
               <<"_design", _/binary>> ->
                       builtin_results(Style, Revs);
  
positive.code: changes_enumerator(DocInfo, Acc) ->
      #changes_acc{
          filter = FilterFun, callback = Callback, prepend = Prepend,
          user_acc = UserAcc, limit = Limit, resp_type = ResponseType
      } = Acc,
      #doc_info{high_seq = Seq} = DocInfo,
      Results0 = FilterFun(DocInfo),
      Results = [Result || Result <- Results0, Result /= null],
      Go = if (Limit =< 1) andalso Results =/= [] -> stop; true -> ok end,
      case Results of
  
negative.code:             % validate that the ddoc has the filter fun
              #doc{body={Props}} = DDoc,
              couch_util:get_nested_json_value({Props}, [<<"views">>, VName]),
              fun(Db2, DocInfo) ->
                  DocInfos =
                  case Style of
                  main_only ->
  