changeNullnessOfValue(valueNumber, location, fact, isNull);
changeNullnessOfValue(valueNumber, location, fact, nullnessValue);
	private void setTOS(ValueNumberFrame vnaFrame, Location location, DefinitelyNullSet fact, boolean isNull)			throws DataflowAnalysisException {		ValueNumber valueNumber = vnaFrame.getTopValue();		changeNullnessOfValue(valueNumber, location, fact, isNull);	}