class LockListNode<E> extends ListNode<E> {
	private boolean _locked;
	public LockListNode(E item) { 
		super(item); 
	}
	public LockListNode(E item, ListNode<E> next) {
		super(item, next);
	}
	public boolean isLocked() { 
		return _locked; 
	}
	public void lock() { 
		_locked = true; 
	}
}