r\Datum\NumberDatum::setValue PHP Method

    public function setValue($val)
    {
        if (!is_numeric($val)) {
            throw new RqlDriverError("Not a number: " . $val);
        }
        parent::setValue($val);
    }

 public static function decodeServerResponse($json)
 {
     $result = new NumberDatum();
     $result->setValue((double) $json);
     return $result;
 }