The property, real and personal, belonging to the city shall not be liable to be sold or appropriated under any writ of execution of cost bill. The funds belonging to the city, in the hands of any person, firm or corporation, shall not be liable to garnishment, attachment, or sequestration; nor shall the city be liable to garnishment on account of any debt it may owe or funds or property it may have on hand or owing to any person. Neither the city nor any of its officers or agents shall be required to answer any such writ of garnishment on any account whatever. The city shall not be obligated to recognize any assignment of wages or funds by its employees, agents or contractors.