public class LinkedSimpleCollection<E> implements SimpleCollection<E> {
  Node<E> first = null;

  public boolean add(E element) {
    Node<E> newnode = new Node<E>(element, first);
    first = newnode;
    return true;
  }
  
  public boolean contains(Object o) {
    for (Node<E> current = first; current != null; current = current.next) {
      if ( (current.element == null && o == null)
          || current.element.equals(o)) {
        return true;
      }
    }
    return false;
  }
  
  public SimpleIterator<E> iterator() {
    return new LinkedSimpleIterator<E>(this);
  }
}