anchor.diff:                                           AccIn
                                    end
                            end, [], DB),
  +    %% see HINT in foldl/3
       lists:foldr(Fun, Acc, Data).
   
   %% @doc foldr iterates over DB and applies Fun(Entry, AccIn) to every element
   %%      encountered in Interval. On the first call AccIn == Acc0. The iteration
   %%      stops as soon as MaxNum elements have been encountered.
  +%%      Returns a potentially larger-than-memory dataset. Use with care.
   -spec foldr(DB::db(), Fun::fun((Entry::entry(), AccIn::A) -> AccOut::A), Acc0::A,
                                  Intervall::db_backend_beh:interval(), MaxNum::non_neg_integer()) -> Acc1::A.
   foldr({DB, _FileName}, Fun, Acc, Interval, MaxNum) ->
  
positive.code:                                          AccIn
                                   end
                           end, [], DB),
      lists:foldl(Fun, Acc, Data).
  
  %% @doc foldl iterates over DB and applies Fun(Entry, AccIn) to every element
  %%      encountered in Interval. On the first call AccIn == Acc0. The iteration
  %%      stops as soon as MaxNum elements have been encountered.
  -spec foldl(DB::db(), Fun::fun((Entry::entry(), AccIn::A) -> AccOut::A), Acc0::A,
                                 Intervall::db_backend_beh:interval(), MaxNum::non_neg_integer()) -> Acc1::A.
  foldl({DB, _FileName}, Fun, Acc, Interval, MaxNum) ->
  
negative.code:     toke_drv:delete(DB, ?IN(Key)),
      State.
  
  %% @doc Returns the name of the DB specified in @see new/1.
  -spec get_name(DB::db()) -> nonempty_string().
  get_name({_DB, FileName}) ->
      FileName.
  