The municipality, at any time after making a contract for the construction of any improvement to be financed in whole or in part by assessments, under authority of any chapter of this title, or prior thereto but after the period for filing protests against the making of such improvement has expired and the protests filed, if any, have been heard and determined to be insufficient, and in anticipation of the levy and collection of such assessments and of any taxes or revenues derived from service charges pledged to pay for such improvement, may issue warrants or improvement bonds on the fund created for such improvement. The municipality is responsible to the holders of the warrants or improvement bonds for the proper advertisement and award of a contract or contracts or provision by other means for the completion of the improvement; for the acquisition of all land, easements, licenses, and permits required for such completion; and for the valid and final levy of special assessments upon all properties within the improvement district to be benefited by the improvement, in an aggregate principal amount equal to the total cost of the improvement as finally ascertained, less the portions thereof, if any, determined to be paid from taxes, service charges, and any other source. The issuance of the warrants or improvement bonds constitutes a representation and covenant binding upon the municipality that the aggregate benefits to be derived from the making of the improvement by the properties to be assessed therefor are not less than the aggregate amount of the special     assessments so required to be levied. The warrants or improvement bonds shall be issued and shall mature in such amounts as in the judgment of the governing body will be provided for, at or before the maturity dates specified, by the taxes and assessments to be levied and spread and the revenues pledged therefor. In lieu of issuing definitive warrants or improvement bonds on any such fund, the governing body may by resolution authorize the issuance and sale of temporary warrants or temporary improvement bonds maturing in not to exceed three years from the date of issue of the first such warrant or temporary improvement bonds, to be repaid with interest from the proceeds of definitive warrants or improvement bonds maturing as hereinabove required, which the governing body shall issue and sell at or before the maturing date of said temporary warrants or temporary improvement bonds, in the amount required, with moneys theretofore received in such fund, to pay the total cost of the improvement and all temporary warrants or temporary improvement bonds theretofore issued on the fund, with interest then accrued thereon. The warrants or temporary improvement bonds must bear interest at a rate or rates and must be sold at a price, not less than ninety-eight percent of par, resulting in an average net interest cost not to exceed twelve percent per annum payable annually or semiannually, except that there is no interest rate ceiling on an issue sold at public sale or to the state of North Dakota or any of its agencies or instrumentalities. The definitive warrants or improvement bonds may bear interest at a rate or rates higher or lower than those borne by the temporary warrants or temporary improvement bonds, as determined by the governing body in effecting the sale thereof. In the sale of temporary warrants or temporary improvement bonds, the municipality may by resolution of the governing body agree to issue to the holder or holders thereof definitive warrants or improvement bonds upon specified terms as to interest, maturity, redemption provisions, and all other pertinent details, in the event that the municipality is unable to sell definitive warrants or improvement bonds to others upon more favorable terms. Coupons representing the interest for each year or lesser period may be attached to the warrants, whether definitive or temporary, or improvement bonds or temporary improvement bonds. All such warrants or bonds shall be negotiable within the meaning of and for all the purposes specified in title 41, and, to the same extent as general obligation bonds of the issuing municipality, are valid investments of the funds of any guardian, trustee, and other fiduciary of any kind or nature, any bank or other financial institution, any charitable, educational, or eleemosynary institution, and any public corporation or official, municipality, school district, or other political subdivision, including bond sinking funds, special improvement funds, municipal utility funds, and funds of the state of North Dakota and its instrumentalities and agencies.