If the assessment is levied in one installment, the cost of construction or reconstruction of sidewalks may be financed, until the assessment is paid, out of the fund provided for the maintenance of streets or general improvement fund if such cost has been budgeted as an expense of such fund, and when the assessment and the interest thereon are paid they shall be credited to such fund; otherwise, the financing shall be by the issuance of sidewalk scrip or sidewalk bonds.