code: public function order($columns, $order)
      {
          $colArray = array();
  
          if (is_array($columns)) {
              foreach ($columns as $column) {
                  $colArray[] = array($column, $order);
              }
          } else {
              $colArray[] = array($columns, $order);
          }
  
          $this->multiOrder($colArray);
          return $this;
      }
docs: Order objects