System.err.println("realizing nodes");
	private final void realize() {		if (realSet != null)			return;		System.err.println("realizing nodes");		switch (axis) {			case Constants.ATTRIBUTE_AXIS :			case Constants.CHILD_AXIS :				realSet = getNodes(false);				break;			case Constants.DESCENDANT_AXIS :				realSet = getNodes(true);				break;		}	}