/**
  * Evaluate the contao 2 sorting flag into sorting mode.
  *
  * @param ListingConfigInterface|PropertyInterface $config The property to evaluate the flag for.
  *
  * @param int                                      $flag   The flag to be evaluated.
  *
  * @return void
  */
 protected function evalFlagSorting($config, $flag)
 {
     if ($flag < 0 || $flag > 12) {
         return;
     }
     if ($flag % 2 == 1) {
         $config->setSortingMode(ListingConfigInterface::SORT_ASC);
     } else {
         $config->setSortingMode(ListingConfigInterface::SORT_DESC);
     }
 }