/// <summary>
        /// Sell the currency
        /// </summary>
        /// <param name="curency"></param>
        /// <param name="amount">The amount in the specified currency</param>
        /// <returns>The amount in the common currency</returns>
        public double Sell(Currencies curency, double amount)
        {
            ExchangeRateDal dal = new ExchangeRateDal();
            double rate = dal.GetRate(curency.ToString());
            if (rate == 0)
                return amount;

            return amount / rate * (1 - Commission); ;
        }
 /// <summary>
 /// Buy the Currency
 /// </summary>
 /// <param name="curency"></param>
 /// <param name="amount">The amount in the common currency</param>
 /// <returns>The value in the specified currency</returns>
 public double Buy(Currencies curency, double amount)
 {
     ExchangeRateDal dal = new ExchangeRateDal();
     double rate = dal.GetRate(curency.ToString());
     return amount * rate * (1 - Commission);
 }