code: public function setPieces($pieces)
      {
          if ($pieces && !$pieces instanceof PieceBag) {
              $pieces = new PieceBag(is_array($pieces) ? $pieces : []);
          }
          return $this->setParameter('pieces', $pieces);
      }
docs: Set the pieces in this order
  
  @param PieceBag|array $pieces An array of items in this order
  @return $this