src/RunOpenCode/ExchangeRate/Utils/CurrencyCodeUtil.php
public static function exists($currencyCode)
    {
        $currencyCode = trim(strtoupper($currencyCode));

        return array_key_exists($currencyCode, self::$codes);
    }
public static function exists($currencyCode)
    {
        $currencyCode = trim(strtoupper($currencyCode));

        return array_key_exists($currencyCode, self::$codes);
    }
Check if currency code exists.

@param string $currencyCode ISO 4271 currency code.
@return bool TRUE if exists.