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

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