public static void CreditOperation(this MT4Manager mt4, int login, double amount, int codePage, [Optional] string comment, [Optional] DateTime expiration) { var operation = new MT4CreditOperation() { Login = login, Amount = amount, Comment = comment, Expiration = expiration == DateTime.MinValue ? mt4.ServerTime().AddMonths(50) : expiration }; mt4.CreditOperation(operation, codePage); }