def retrieve(self, order_id, id) :
_, _, line_item = self.http_client.get("<STR_LIT>".format(order_id=order_id, id=id))<EOL>return line_item<EOL>
Retrieve a single line item

Returns a single line item of an order, according to the unique line item ID provided

:calls: ``get /orders/{order_id}/line_items/{id}``
:param int order_id: Unique identifier of a Order.
:param int id: Unique identifier of a LineItem.
:return: Dictionary that support attriubte-style access and represent LineItem resource.
:rtype: dict