Whenever treasury notes are issued and sold as provided in this act, they shall constitute an irrevocable and irrepealable contract between the state of Idaho and the owner of said treasury notes that the portion of the taxes and/or fees pledged for payment thereof provided by this act shall not be reduced so long as any of the treasury notes issued under this act remain outstanding and unpaid, and that the state will cause said taxes or fees to be promptly collected, and sufficient thereof set aside and applied as in this act provided to pay the annual interest and an amount of principal that will be equal to the total amount of the notes issued and outstanding divided by the number of years over which said notes are to be paid, to provide for the payment of such treasury notes and interest according to the terms and priority of issues thereof, and that the legislature shall not reduce the amount of such pledged tax or fee while any of said treasury notes are outstanding; but if all thereof be paid the legislature may reduce such tax or fee to be collected and pledged for payment of any future or new or additional issue of notes sold under this act after such reduction. Any holder of said treasury notes, or any person, or officer, being a party in interest, may by action either at law or in equity enforce and compel the performance of the duties of any officer or person herein mentioned, required by this act.