class Set
{

  /*
   * This exception is thrown by various methods
   * of the Set class. 
   *
   * The constructor takes a string that describes the specific 
   * situation
   */
  public class SetException extends Exception
  {
    public SetException (String s)
    { 
      super (s);
    }
  }


  /*
   * Declare any instance variables here
   */


  /*
   * This is the default constructor. 
   * It just creates an empty set.
   * Basically, it creates an empty linked list.
   */
  public Set()
  {
    /*
     * Your code here
     */
  }


  /*
   * This is a copy constructor. It creates a new set from
   * an old set
   */
  public Set (Set original) throws SetException
  {
    /*
     * Your code here
     */
  }


  /*
   * Returns the items in the set as a string
   */
  public String toString()
  {
    /*
     * Your code here
     */
  }


  /*
   * Returns true if the item is in the set and false
   * otherwise
   */
  public boolean member(Object item)
  {
    /*
     * Your code here
     */
  }


  /*
   * This method should add an item to the set. It should throw 
   * an exception if the item is already in the set.
   *
   * Specifically, you should define a SetException and throw
   * this exception. When you create a new instance of this 
   * exception, you should set its value to "Item already in set."
   */

  public void addItem (Object item) throws SetException
  {
    /*
     * Your code here
     */
  }

  /*
   * This method should add all of the items from the newItems set
   * into the original set. It should throw an exception
   * upon discovering that any requested item is already in the set.
   *
   * Specifically, you should define a SetException and throw
   * this exception. When you create a new instance of this 
   * exception, you should set its value to "Item already in set."
   */

  public void addItems (Set newItems) throws SetException
  {
    /*
     * Your code here
     */
  }


  /*
   * This method should remove an item from the set. It should throw 
   * an exception if the item is not in the set.
   *
   * Specifically, you should define a SetException and throw
   * this exception. When you create a new instance of this 
   * exception, you should set its value to "Item not already in set."
   */

  public void removeItem (Object item) throws SetException
  {
    /*
     * Your code here
     */
  }

  /*
   * This method should remove all of the items in the "items" Set
   * from the current set. It should throw an exception 
   * upon discovering that any of the specified items is not in the
   * target set.
   *
   * Specifically, you should define a SetException and throw
   * this exception. When you create a new instance of this 
   * exception, you should set its value to "Item not already in set."
   */

  public void removeItems (Set items) throws SetException
  {
    /*
     * Your code here
     */
  }

  /*
   * This returns a new set that contains every element in
   * the original set and the set provided by the user
   */
  public Set union (Set in_set) throws SetException
  {
    /*
     * Your code here
     */
  }


  /*
   * This returns a new set that contains only those elements
   * in the original set and the set provided by the user
   */
  public Set intersection (Set in_set) throws SetException
  {
    /*
     * Your code here
     */
  }


  /*
   * This returns a new set that contains only those elements
   * in the original set or the set provided by the user, but
   * not both.
   */
  public Set xor (Set in_set) throws SetException
  {
    /*
     * Your code here
     */
  }

  /*
   * This returns true if the specified set is a proper subset of the target
   * set and false otherwise.
   */
  public boolean subset (Set subset) throws SetException
  {
    /*
     * Your code here
     */
  }


  /*
   * This should be a test driver.
   * It should perform no user or file I/O whatsoever.
   * Instead, it should be a static test set that convinces 
   * us that your Set class works. It should test all of the
   * special cases, all of the boundary cases, and the common
   * cases.
   */
  public static void main (String []argv) throws SetException
  {
    /*
     * Your code here
     */
  }
}