Subject to the applicable provisions of the general laws of the State, the Council shall have authority to borrow money in anticipation of the payment of special assessments or combination of special assessments made for the purpose of defraying the cost of any public improvement and to issue bonds for the borrowing. These special assessment bonds may be either an obligation of the special assessment district or districts or both an obligation of the special assessment district or districts and a general obligation of the City. All collections on each special assessment roll or combination of rolls shall be set apart in a separate fund for the payment of the principal and interest of the bonds issued in anticipation of the payment of these special assessments and shall be used for no other purpose.