All real property excluded from a county library district as provided in sections 182.130 and 182.480 shall thereafter be subject to the levy of taxes for the payment of any bonded indebtedness of the county library district outstanding at the time or exclusion and for no other purpose; provided, however, that any buildings and improvements thereafter erected or constructed on the excluded real property, and all machinery and equipment thereafter installed or placed therein or thereon, and all tangible, personal property thereafter located therein or thereon shall not be subject to the levy of any taxes of the county library district. In lieu of the continuing taxation of the real property excluded from the county library district, the governing body of the city in which the excluded property is situated may pay to the county library district a sum equal to that portion of the total bonded indebtedness of the county library district that the assessed valuation of the excluded property bears to the total assessed value of the county library district prior to the exclusion, after which payment the excluded property shall no longer be subject to any levy of taxes by the county library district. The funds paid to the county library district shall be used for retiring the bonds of the county library district.