### Description In the ICU dataset, there are values that are no longer relevant / no longer used today (e.g. the BEF currency), and I wanted to know if you would be interested in adding methods that allow us to determine whether a given currency is obsolete/active based on ICU metadata: see https://github.com/unicode-org/cldr/blob/main/common/supplemental/supplementalData.xml This would enable us to offer more up-to-date selections. I would be happy to develop this feature if you find it interesting. WDYT ? ### Example ```php <?php use Symfony\Component\Intl\Currencies; Currencies::isObsolete('BEF'); // Return true ```