A structure, or part of a structure, that serves as the undivided dwelling place for habitation of one or more persons constituting a single nuclear family. A housing unit is a house, an apartment, a hut, a mobile home, a tent, a shanty, a group of rooms, or a single room that is occupied (or if vacant, is intended for occupancy) as separate living quarters. Separate living quarters are those in which the occupants live and eat separately from any other persons in the building and that have direct access from the outside of the building or through a common hall. For example, a building with six apartments counts as six housing units.