public interface MySet<E> extends java.lang.Iterable<E> {
  /** Remove all elements from this set */
  public void clear();
  
  /** Return true if the element is in the set */
  public boolean contains(E e);
  
  /** Add an element to the set */
  public boolean add(E e);

  /** Remove the element from the set */
  public boolean remove(E e);

  /** Return true if the set contains no elements */
  public boolean isEmpty();

  /** Return the number of elements in the set */
  public int size();
}