docs: private static synchronized Tree getCollocationProcessedTree(Tree tree,
                                                                 HeadFinder hf) {
      if (wnc == null) {
        try {
          Class<?> cl = Class.forName("edu.stanford.nlp.trees.WordNetInstance");
          wnc = (WordNetConnection) cl.newInstance();
        } catch (Exception e) {
          System.err.println("Couldn't open WordNet Connection.  Aborting collocation detection.");
          e.printStackTrace();
          wnc = null;
        }
      }
      if (wnc != null) {
        CollocationFinder cf = new CollocationFinder(tree, wnc, hf);
        tree = cf.getMangledTree();
      } else {
        System.err.println("ERROR: WordNetConnection unavailable for collocations.");
      }
      return tree;
    }