public function calculateExchangeRate(
        CurrencyInterface $currencyFrom,
        CurrencyInterface $currencyTo
    ) {
        $currencyFromIso = $currencyFrom->getIso();
        $currencyToIso = $currencyTo->getIso();

        if ($currencyFromIso == $currencyToIso) {
            return 1.0;
        }

        return $this
            ->calculateExchangeRateBetweenIsos(
                $currencyFromIso,
                $currencyToIso
            );
    }