public static function getSubUnit($currencyCode)
    {
        $subunits = static::getCurrencyData($currencyCode)['sub_unit'];
        if (!is_int($subunits)) {
            throw new UnexpectedValueException(sprintf(
                'The currency sub-units value must be an integer; "%s" given',
                is_object($subunits) ? get_class($subunits) : gettype($subunits)
            ));
        }
        if ($subunits < 1) {
            throw new UnexpectedValueException(sprintf(
                'The currency sub-units value must be greater than 1; "%s" given',
                $subunits
            ));
        }
        return $subunits;
    }