arguments[1].Assign(oldleft); return arguments[0].Assign(oldright);
if (arguments[0].Assign(oldright) == null) { return null; } if (arguments[1].Assign(oldleft) == null) { return null; } return arguments[0];
	public vDescriptor nextval() {		if (oldleft == null) {			oldleft = arguments[0].deref();			oldright = arguments[1].deref();			arguments[1].Assign(oldleft);			return arguments[0].Assign(oldright);		} else {			arguments[0].Assign(oldleft);			arguments[1].Assign(oldright);			return null;		}	}