public T find( T x )
        {
            nullNode.element = x;
            current = header.right;

            for( ; ; )
            {
                if( x.compareTo( (T)current.element ) < 0 )
                    current = current.left;
                else if( x.compareTo( (T)current.element ) > 0 ) 
                    current = current.right;
                else if( current != nullNode )
                    return (T)current.element;
                else
                    return null;
            }
        }