Article 550 of Civil Code

1 - No account shall be taken of a change in the value of the equivalent at the time of return. 2 - If an equivalent of the thing borrowed ceases to be available on the market, the lender shall have the option either to wait until the thing returns to the market, whereupon the borrower shall return its equivalent, or to demand from the borrower the value of the thing at the time and place at which return is due.