src/ApiClient.php
public function getExchangeRate($currency1, $currency2)
    {
        $list = $this->getExchangeRates([[$currency1, $currency2]]);

        return isset($list[0]) ? $list[0] : null;
    }
public function getExchangeRate($currency1, $currency2)
    {
        $list = $this->getExchangeRates([[$currency1, $currency2]]);

        return isset($list[0]) ? $list[0] : null;
    }
Get exchange rate for two currencies. Accepts concatenated ISO 4217 currency codes.

@param string $currency1
@param string $currency2

@return Quote|null