private static ArrayList<HashMap<String, String>> getExs(String attribute,
			String vk, ArrayList<HashMap<String, String>> examples) {
		ArrayList<HashMap<String, String>> exs = new ArrayList<HashMap<String, String>>();
		for (HashMap<String, String> example : examples) {
			if (example.get(attribute).equals(vk)) {
				exs.add(example);
			}
		}
		return exs;
	}