public function convertToUSD(Money $money, ExchangeRate $exchangeRate)
{
if ($exchangeRate->getCurrency() != $money->getCurrency()) {
throw new InvalidCurrencyExchangeException();
}
$rate = $exchangeRate->getRate();
$amountInUSD = $money->divide($rate);
return Money::create($amountInUSD->getAmount(), Currency::CODE_USD);
}