A county, city, municipal corporation, or district may do any and all things necessary under federal law or rule of a federal department, agency, mandatory, or authority, to secure monetary aid either as a loan or as an outright appropriation:
(a)
To reduce any of its indebtedness.
(b)
To fund or refund any such indebtedness, whether relating to general obligation bonds or to the obligations represented by special assessment bonds for the unpaid principal upon any assessment levied prior to September 15, 1935 pursuant to state law in which the lien
is special as to a particular property described in the assessment or bond, or whether the bonds are to be paid and discharged from an annual levy in accordance with the assessed value of all of the lands in a district.