preFeatures = new Vector<PreFeature>();
//TODO register features
//preFeatures.add(new ElementRemovalPreFeature());
preFeatures.add(new NumberOfChildrenPreFeature());
preFeatures.add(new NumberOfDescendentsPreFeature());
preFeatures.add(new ChildrenDepthPreFeature());
preFeatures.add(new NumberOfSiblingSameTypePreFeature());
}