The seller of goods is deemed to be an unpaid seller within the meaning of this Title:
(1) When the whole of the price has not been paid or tendered;
(2) When a bill of exchange or other negotiable instrument has been received as conditional payment, and the condition on which it was received has been broken by reason of the dishonor of the instrument, the insolvency of the buyer, or otherwise.
In articles 1525 to 1535 the term "seller" includes an agent of the seller to whom the bill of lading has been indorsed, or a consignor or agent who has himself paid, or is directly responsible for the price, or any other person who is in the position of a seller. (n)