function validateCurrency(type, currency) {
    if (type === 'members') {
        return null;
    }

    if (!currency || (currency && typeof currency !== 'string' || currency.length > 3)) {
        return 'usd';
    }

    return currency;
}
@param {'arr'|'members'} type
@param {string|null} currency

@returns {string}