/**
  * Get exchanged amount
  *
  * @param int $amount
  * @param string $originalCurrency
  * @param string $destinationCurrency 
  */
 public function exchange($amount, $originalCurrency, $destinationCurrency = null)
 {
     if (null !== $destinationCurrency) {
         if ($originalCurrency == $destinationCurrency) {
             return $amount;
         }
     }
     $amount = new Decimal($amount);
     if ($originalCurrency == CurrencyCode::PLN) {
         return $amount->mul($this->ratio)->getAmount();
     } else {
         return $amount->getAmount() / $this->ratio;
     }
 }
 public function removeFrozen($amount)
 {
     if (!$amount instanceof Decimal) {
         $amount = new Decimal($amount);
     }
     $this->frozen = Decimal::create($this->frozen)->sub($amount)->getAmount();
 }