When a credit or other incorporeal right in litigation is sold, the debtor shall have a right to extinguish it by reimbursing the assignee for the price the latter paid therefor, the judicial costs incurred by him, and the interest on the price from the day on which the same was paid. A credit or other incorporeal right shall be considered in litigation from the time the complaint concerning the same is answered. The debtor may exercise his right within thirty days from the date the assignee demands payment from him. (1535)