All bonds issued under Sections 21-27-161 through 21-27-191 shall be and are hereby exempt from inclusion in debts in determining whether additional bonds may be issued by such municipality and are declared to be legal and authorized investments for banks, savings banks, trust companies, building and loan associations, savings and loan associations, insurance companies, fiduciaries, trustees and for the sinking fund of municipalities, towns, villages, school districts or any other political corporation or subdivision of the State of Mississippi.