anchor.diff:                                      bitcask:fold_keys(Ref1,
                                                         FoldFun,
                                                         {Acc, sets:new()}),
  +                                bitcask:close(Ref1),
                                   Acc1;
                               {error, Reason} ->
                                   {error, Reason}
  
positive.code:                         case bitcask:open(filename:join(DataRoot, DataFile),
                                            ReadOpts) of
                              Ref1 when is_reference(Ref1) ->
                                  bitcask:fold(Ref1, FoldFun, Acc);
                              {error, Reason} ->
                                  {error, Reason}
                          end
  
negative.code:                         case bitcask:open(filename:join(DataRoot, DataFile),
                                            ReadOpts) of
                              Ref1 when is_reference(Ref1) ->
                                  FoldResults =
                                      bitcask:fold_keys(Ref1, FoldFun, Acc),
                                  bitcask:close(Ref1),
                                  FoldResults;
                              {error, Reason} ->
                                  {error, Reason}
                          end
  