mapToCurrencyIso example

public function serialize(Config $config, Field $entity, $prices): iterable
    {
        if (!$prices) {
            return;
        }

        $isoPrices = [];
        foreach ($prices as $price) {
            $price = $price instanceof Struct ? $price->jsonSerialize() : $price;
            $currencyId = $price['currencyId'];
            $currency = $this->mapToCurrencyIso($currencyId);

            if (isset($price['listPrice']) && $price['listPrice'] instanceof Struct) {
                $price['listPrice'] = $price['listPrice']->jsonSerialize();
            }

            $isoPrices[$currency] = $price;
            if ($currencyId === Defaults::CURRENCY) {
                $isoPrices['DEFAULT'] = $isoPrices[$currency];
            }
        }