Section 56.   SYSTEM OF TAXATION.
   Subject to the state Constitution, and except as forbidden by it or by state legislation, the council shall have full power to provide by ordinance for a system of local taxation and to change the same from time to time. Insofar as the city procures a revenue from taxes upon real and personal property as such, it shall conform as fully as possible to the general state law as to the assessment of such property and the collection of such taxes.