public HeadTreeNode(Sexp tree) { this(tree, new IntCounter());
HeadTreeNode(Word headWord, HeadTreeNode headChild, ArrayList preMods, ArrayList postMods) { this.headWord = headWord; this.headChild = headChild; this.preMods = preMods; this.postMods = postMods;
  public HeadTreeNode(Sexp tree) {    this(tree, new IntCounter());  }