All bonds issued under this chapter shall be signed by the presiding officer of the governing body or bodies issuing the same, and the official seal or seals of such governing body or bodies shall be affixed thereto, attested by the clerk or secretary of such governing body or bodies. The interest coupons to be attached to such bonds may be executed by the facsimile signatures of said officers. Whenever any such bonds shall have been signed by the officers herein designated to sign the bonds who were in office at the time of such signing but who may have ceased to be such officers prior to the sale and delivery of such bonds, or who may not have been in office on the date such bonds may bear, the signatures of such officers upon such bonds and coupons shall nevertheless be valid and sufficient for all purposes and have the same effect as if the person so officially signing such bonds had remained in office until the delivery of the same to the purchaser or had been in office on the date such bonds may bear.