anchor.diff:  %% @doc Creates new DB handle named DBName with options.
   -spec new_db(DirName::string(), HanoiOptions::[hanoidb_config_option()]) -> db().
   new_db(DBName, HanoiOptions) ->
  -	BaseDir = [config:read(db_directory), "/", atom_to_list(node())],
  +    BaseDir = [config:read(db_directory), "/", atom_to_list(node())],
       _ = case file:make_dir(BaseDir) of
               ok -> ok;
               {error, eexist} -> ok;
               {error, Error0} -> erlang:exit({db_toke, 'cannot create dir', BaseDir, Error0})
  -    end,
  +        end,
       
       % HanoiDB stores not in a file but a dir store
       FullDBDir = lists:flatten([BaseDir, "/", DBName]),
       case hanoidb:open(FullDBDir, HanoiOptions) of 
  -		{ok, Tree} ->	{Tree, DBName};
  -		ignore ->	log:log(error, "[ Node ~w:db_hanoidb ] ~.0p", [self(), ignore]),
  -                          erlang:error({hanoidb_failed, ignore});
  -		{error, Error2} -> log:log(error, "[ Node ~w:db_hanoidb ] ~.0p", [self(), Error2]),
  -                          erlang:error({hanoidb_failed, Error2})
  -	end.
  +        {ok, Tree} ->    {Tree, DBName};
  +        ignore ->    log:log(error, "[ Node ~w:db_hanoidb ] ~.0p", [self(), ignore]),
  +                     erlang:error({hanoidb_failed, ignore});
  +        {error, Error2} -> log:log(error, "[ Node ~w:db_hanoidb ] ~.0p", [self(), Error2]),
  +                           erlang:error({hanoidb_failed, Error2})
  +    end.
   
   %% @doc Closes the DB named DBName keeping its data on disk.
   -spec close(DB::db()) -> true.
  
positive.code: %% @equiv foldr(DB, Fun, Acc0, Interval, get_load(DB))
  %% @doc   Returns a potentially larger-than-memory dataset. Use with care.
  -spec foldr(DB::db(), Fun::fun((Key::key(), AccIn::A) -> AccOut::A), Acc0::A,
                                 Interval::db_backend_beh:interval()) -> Acc1::A.
  foldr(State, Fun, Acc, Interval) ->
      foldr_helper(State, Fun, Acc, Interval, -1).
  
  
negative.code: %% @equiv foldl(DB, Fun, Acc0, Interval, get_load(DB))
  %% @doc   Returns a potentially larger-than-memory dataset. Use with care.
  -spec foldl(DB::db(), Fun::fun((Key::key(), AccIn::A) -> AccOut::A), Acc0::A,
              Interval::db_backend_beh:interval()) -> Acc1::A.
  foldl(State, Fun, Acc, Interval) ->
      %hanoidb:fold_range(DB, Fun, Acc, #key_range{from_key=K1, to_key=K2}). % TODO check it is possible
      foldl_helper(State, Fun, Acc, Interval, -1).
  
  %% @doc foldl iterates over DB and applies Fun(Entry, AccIn) to every element
  