/**
 * Extend Stack by adding a size, a search, a find
 * and a toString method.
 */
public interface SearchableStack<E> extends Stack<E> {
  
  /**
   * Check whether a matching element is contained.
   */
  public boolean search( E o ); 
  
  /**
   * Return a matching element.
   */
  
  public E find( E o );  
  
  /**
   * Return my size.
   */
  public int size();
  
  /**
   * Return a string representation of the stack.
   */
  public String toString();
}