Any municipal corporation, county, city or town, called “municipality” in this part, owning or operating or authorized to acquire or operate any electric generation, transmission or distribution system, is authorized, in any contract or arrangement with the Tennessee Valley authority or any similar governmental agency for the acquisition of any such system or part of a system or the purchase of electric power and energy, to stipulate and agree to such covenants, terms and conditions as the governing body of the municipality may deem appropriate, including, but not limited to, covenants, terms and conditions in respect to the resale rates, financial and accounting methods, services, operation and maintenance practices and the manner of disposing of the revenues, of any such system, and to comply therewith, and any such covenants, terms or conditions heretofore stipulated or agreed to are hereby expressly validated.