code: public function getAttributeOrder($attribute)
      {
          $orders = $this->getAttributeOrders();
  
          return isset($orders[$attribute]) ? $orders[$attribute] : null;
      }
docs: Returns the sort direction of the specified attribute in the current request.
  @param string $attribute the attribute name
  @return bool|null Sort direction of the attribute. Can be either `SORT_ASC`
  for ascending order or `SORT_DESC` for descending order. Null is returned
  if the attribute is invalid or does not need to be sorted.