public static function useCurrency(string $currency, ?string $symbol = null): void
    {
        static::$currency = $currency;
        static::useCurrencySymbol($symbol ?: static::guessCurrencySymbol($currency));
    }
public static function useCurrency(string $currency, ?string $symbol = null): void
    {
        static::$currency = $currency;
        static::useCurrencySymbol($symbol ?: static::guessCurrencySymbol($currency));
    }
public static function useCurrency ( string $ currency , ? string $ symbol = null ) : void { static :: $ currency = $ currency ; static :: useCurrencySymbol ( $ symbol ? : static :: guessCurrencySymbol ( $ currency ) ) ; }
Set the currency to be used when billing users.

@param string $currency
@param string|null $symbol

@throws Exception
Set the currency to be used when billing users .