class MyList {
  private ListElement head, tail; //Forward declaration
  void add(Object value) {
    if (tail != null) {
      tail.next = new ListElement(value);
      tail = tail.next;
    }
    else {
      head = tail = new ListElement(value);
    }
  }
  Object remove() 
  {
    assert head != null; // don't remove on empty list
    Object result = head.value;
    head = head.next;
    if (head == null) { //was that the last?
      tail = null;
    }
    return result;
  }
  //Nested class needed only in the implementation of MyList
  private class ListElement {
    ListElement(Object value) {this.value = value;}
    Object value;
    ListElement next; //defaults to null as desired
  }
}