sclass OccTree2 {

  OccTree2 parent;

  E e;

  new L<OccTree2> next;

  int count; // This isn't accurate after replaceWith and stuff

  *() {}

  *(E *e) {}

  void addScript(L<E> script) {

    OccTree2 node = this;

    ++count;

    for (E c : script)

      (node = node.getOrMakeFollowUp(c)).count++;

  }

  OccTree2 getOrMakeFollowUp(E e) {

    OccTree2 node = followUp(e);

    if (node == null)

      next.add(node = newChild(e));

    ret node;

  }

  OccTree2 followUp(E e) {

    for (OccTree2 t : next)

      if (eq(t.e, e))

        ret t;

    null;

  }

  L<E> followUpKeys() {

    ret collect(next, "e");

  }

  OccTree2 newChild(E e) {

    OccTree2 child = new OccTree2(e);

    child.parent = this;

    ret child;

  }

  // size including all nodes

  int size() {

    int n = 1;

    for (OccTree2 t : next)

      n += t.size();

    ret n;

  }

  L<OccTree2> allLeaves() { new L l; collectLeaves(l); ret l; }

  // does not include root node as it has no input line associated

  L<OccTree2> allNodes() { new L l; collectNodes(l); ret l; }

  void collectLeaves(L<OccTree2> l) {

    if (isLeaf())

      l.add(this);

    else

      for (OccTree2 t : next)

        t.collectLeaves(l);

  }

  void collectNodes(L<OccTree2> l) {

    if (!isRoot())

      l.add(this);

    for (OccTree2 t : next)

      t.collectNodes(l);

  }

  bool isRoot() { ret e == null; }

  bool isLeaf() {

    ret !isRoot() && isEmpty(next);

  }

  int level() {

    int n = 0;

    OccTree2 node = this;

    while (node.parent != null) {

      ++n;

      node = node.parent;

    }

    ret n;

  }

  void replaceWith(OccTree2 n) {

    int i = parent.next.indexOf(this);

    parent.next.set(i, n);

    n.parent = parent;

    parent = null;

  }

}