code	system_type	meaning
0	new_const	no
1	new_const	yes
1	sewer_type	none
2	sewer_type	private
3	sewer_type	public
0	central_air	no
1	central_air	yes
2	fuel_type	gas
3	fuel_type	electric
4	fuel_type	oil
2	heat_type	hot air
3	heat_type	hot water
4	heat_type	electric