@SuppressWarnings("unchecked")
    public static <T extends Number & Comparable> WindowOver<T> ntile(T num) {
        return new WindowOver<T>((Class<T>) num.getClass(), SQLOps.NTILE, ConstantImpl.create(num));
    }
@ SuppressWarnings ( "unchecked" ) public static < T extends Number & Comparable > WindowOver < T > ntile ( T num ) { return new WindowOver < T > ( ( Class < T > ) num . getClass ( ) , SQLOps . NTILE , ConstantImpl . create ( num ) ) ; }
divides an ordered data set into a number of buckets indicated by expr and assigns the
appropriate bucket number to each row

@param num bucket size
@return ntile(num)