anchor.diff:  foldl(Iterator, _Acc, Table) ->
       Exec = fun() -> mnesia:foldl(Iterator, [], Table) end,
       case mnesia:is_transaction() of
  -    true ->
  -        Exec();
  -    false ->
  -        mnesia:activity(transaction, Exec)
  +        true ->
  +            Exec();
  +        false ->
  +            mnesia:activity(transaction, Exec)
       end.
   
   %% @doc Clear all objects from given table in mnesia DB.
  
positive.code:             {error, Error}
      end;
  delete(Table, Key)->
     case mnesia:is_transaction() of
         true ->
             Delete = fun() -> mnesia:delete({Table, Key}) end,
             mnesia:activity(transaction, Delete);
         false ->
              case mnesia:dirty_delete({Table, Key}) of
              ok ->
                  ok;
              Error ->
                  {error, Error}
              end
      end.
  
  
negative.code: -spec select(Table :: atom(), Key :: term()) -> tuple().
  select(Table, Key)->
      Select = fun () ->
                       case mnesia:read({Table, Key}) of
                           [Record] -> [{Key,Record}];
                           _ -> []
                       end
               end,
      mnesia:activity(transaction, Select).
  
  %% @doc Select using a match spec.
  