public interface List {
	void removeFirst();
	void removeLast();
	boolean remove(int i);
	void addFirst(Object o);
	void addLast(Object o);
	boolean add(int i,Object o);
	void sort(Sorter sorter);
	Object get(int i);
	int length();
	int size();
	boolean contains(Object o);
	List reverse();
}