public static <T extends Number> WindowOver<T> stddevDistinct(Expression<T> expr) {
        return new WindowOver<T>(expr.getType(), SQLOps.STDDEV_DISTINCT, expr);
    }
public static < T extends Number > WindowOver < T > stddevDistinct ( Expression < T > expr ) { return new WindowOver < T > ( expr . getType ( ) , SQLOps . STDDEV_DISTINCT , expr ) ; }
returns the sample standard deviation of expr, a set of numbers.

@param expr argument
@return stddev(distinct expr)