sclass MinimalChain<A> implements Iterable<A> {
  A element;
  MinimalChain<A> next;

  *() {}
  *(A *element) {}
  *(A *element, MinimalChain<A> *next) {}
  
  toString { ret str(toList()); }
  
  ArrayList<A> toList() {
    new ArrayList<A> l;
    MinimalChain<A> c = this;
    while (c != null) {
      l.add(c.element);
      c = c.next;
    }
    ret l;
  }
  
  // TODO: optimize
  public Iterator<A> iterator() { ret toList().iterator(); }
}