The City shall have the power to join with any governmental unit or agency, or with any number or combination thereof, by contract or otherwise as may be permitted by law, to have performed (a) jointly, or (b) by one or more of them for or on behalf of the other or others, or (c) by any other person, firm, or corporation, any function which is permitted to be so performed by law by such governmental unit or agency, and to provide for the financing thereof.