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

def list(self, order_id, **params):
        """
        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
        """

        _, _, line_items = self.http_client.get("/orders/{order_id}/line_items".format(order_id=order_id), params=params)
        return line_items