code: def list(self, order_id, **params):
          
  
          _, _, line_items = self.http_client.get("/orders/{order_id}/line_items".format(order_id=order_id), params=params)
          return line_items
docs: Retrieve order's line items
  
          Returns all line items associated to order
  
          :calls: ``get /orders/{order_id}/line_items``
          :param int order_id: Unique identifier of a Order.
          :param dict params: (optional) Search options.
          :return: List of dictionaries that support attriubte-style access, which represent collection of LineItems.
          :rtype: list