No bonds shall be payable in installments, but each shall be payable in full on the date specified therein by the board, which need not be an anniversary of the date of the bond.

The board may provide that any bond issued by the district may be subject to call and retirement prior to maturity at such times and prices and upon such other terms as the board may specify. If a bond is subject to call and retirement prior to maturity that fact shall be stated in the bond.