public ListCurrencies GetCurrencies()
        {
            if (_listCurrencies != null)
            {
                return(_listCurrencies);
            }

            _listCurrencies = GetBaseHttpTask <ListCurrencies>("list");

            if (_listCurrencies.Success)
            {
                return(_listCurrencies);
            }

            _listCurrencies = null;

            throw new DataException("Error in GetCurrencies");
        }
 public void ClearCache()
 {
     _currency       = null;
     _listCurrencies = null;
 }