public static Tree xTree(List<? extends HasWord> words) {
TreeFactory lstf = new LabeledScoredTreeFactory();
List<Tree> lst2 = new ArrayList<Tree>();
for (HasWord obj : words) {
String s = obj.word();
Tree t = lstf.newLeaf(s);
String tag = "XX";
if (obj instanceof HasTag) {
if (((HasTag) obj).tag() != null) {
tag = ((HasTag) obj).tag();
}