public static function format($number, $decimals = null, $decimalPoint = null,
                                  $thousandsSeparator = null)
    {
        if (is_null($decimals)) {
            $decimals = self::$decimals;
        }
        if (is_null($decimalPoint)) {
            $decimalPoint = self::$decimalPoint;
        }
        if (is_null($thousandsSeparator)) {
            $thousandsSeparator = self::$thousandsSeparator;
        }
        return number_format($number, $decimals, $decimalPoint, $thousandsSeparator);
    }