public function rates(string $currency, string $date) : Rates
    {
        $rates = $this->getBaseRates($currency, $date);
        if (empty($rates)) {
            $rates = $this->convert($this->download($date));
            if ($currency !== 'EUR') {
                //Set USD base rate
                $this->setBaseRates($rates->convertBaseRatesToUSD());

                if ($currency !== 'USD') {
                    $rates = $rates->convertBaseRateToCurrency($currency);
                    $this->setBaseRates($rates);
                }
            }
            else {
                $this->setBaseRates($rates);
            }
        }

        return $rates;
    }