public boolean contains(Object obj) 
{
return false;
}

 public boolean containsAll(Collection c) 
{
 return c.isEmpty();
}

 public boolean isEmpty() 
{
return true;
}

 public Iterator iterator() 
{
            return emptyIterator();
}

 public int size() 
{
return 0;
}

 public Object[] toArray() 
{
 return new Object[0];
}

 public T[] toArray(T[] a) 
{
            if (a.length  > 0)
                a[0] = null;
            return a;
}