anchor.diff:                                   [?OUT(Entry) | AccIn]
                            end, [], DB),
       %% see HINT in foldl/3
  -    lists:foldr(Fun, Acc, Data).
  +    lists:foldl(Fun, Acc, Data).
   
   %% @equiv foldr(DB, Fun, Acc0, Interval, get_load(DB))
   %% @doc   Returns a potentially larger-than-memory dataset. Use with care.
  
positive.code:                               end
                        end, {MaxNum, []}, DB),
      %% see HINT in foldl/3
      lists:foldl(Fun, Acc, Data).
  
  %% @doc makes a foldr over the whole dataset.
  %%      Returns a potentially larger-than-memory dataset. Use with care.
  
negative.code:     %% HINT
      %% Fun can only be applied in a second pass. It could do a delete (or other
      %% write op) and toke can not handle writes whiles folding.
      %% Since we reversed the order while accumulating reverse it by using lists
      %% fold but "from the other side"
      lists:foldr(Fun, Acc, Data).
  
  %% @equiv foldl(DB, Fun, Acc0, Interval, get_load(DB))
  %% @doc   Returns a potentially larger-than-memory dataset. Use with care.
  