All warrants issued by the city which have been heretofore or may hereafter be presented to the finance director of the city for payment, and which have not been or shall not be paid for want of funds in the treasury, shall bear interest as established by current market conditions from the day of such presentation until paid or called in as hereinafter provided. (Ord. 2934 § 1, 1976; 1957 code § 1.38.010.)