private ArrayList<String> getTreeLeafs(){
		ArrayList<String> leafs = new ArrayList<>();
		for(ArrayList<String> valueList : _tree.values()){
			for(String value : valueList){
				if(_tree.containsKey(value)) continue;
				if(leafs.contains(value)) continue;
				leafs.add(value);
			}
		}
		return leafs;
	}