Let us now proceed to a more specific consideration of the question as to whether or not the instant ordinance either conflicts with state law, or deals with a subject matter forbidden to the city because of state preemption of the 'field'. The conclusion of the appellate department that the ordinance is valid is strongly supported by In re Boza, 41 Cal.App.2d 25, 29-30, 106 P.2d 29. We recognize, of course, that a fatal conflict between a city ordinance and controlling state law may exist in various situations.