Where the officers of any incorporated city of this state, prior to July 1, 1929, have purchased, erected, operated, maintained, enlarged, improved, extended, or leased from any person, firm, or corporation, or sold or leased to any person, firm, or corporation, any electric plant, system, or line, or part thereof, such acts of such municipal officers are legalized and validated.
N.D.C.C. § 1-07-08