anchor.diff:  -spec open(Dir :: string(), [open_opt()]) ->
                     {ok, mstore()} | {error, enoent | not_found | invalid_file}.
   open(Dir, Opts) ->
  -    MStore = apply_opts(#mstore{dir=Dir}, Opts),
       FullIndexRead = proplists:get_bool(preload_index, Opts),
       case open_mfile(Dir, FullIndexRead) of
           {ok, FileSize, Metrics} ->
  -            {ok, MStore#mstore{metrics=Metrics, size=FileSize}};
  +            MStore = apply_opts(#mstore{dir=Dir, metrics=Metrics,
  +                                        size = FileSize}, Opts),
  +            {ok, MStore#mstore{}};
           Error ->
               Error
       end.
  -            
  +
   
   %%--------------------------------------------------------------------
   %% @doc
  
positive.code:     do_fold_idx(IO, Chunk,
                  fun({entry, M}, Acc) ->
                          btrie:store(M, Acc)
                  end, btrie:new(), R);    
  maybe_read_index(IO, _Chunk, _R, false) ->
      file:close(IO),
      delayed.
  
negative.code:         mstore(),
          binary(),
          non_neg_integer()) ->
                      {'error',atom()} |
                      {ok, bitmap:bitmap()}.
  
  bitmap(#mstore{size=S, files=FS, dir=Dir},
         Metric, Time) when
        is_binary(Metric),
        is_integer(Time), Time >= 0 ->
      R = do_get_bitmap(S, FS, Dir, Metric, Time),
  