public static Order sellAt(int index, Decimal price, Decimal amount) {
        return new Order(index, OrderType.SELL, price, amount);
    }
public static Order sellAt ( int index , Decimal price , Decimal amount ) { return new Order ( index , OrderType . SELL , price , amount ) ; }
@param index the index the order is executed
@param price the price for the order
@param amount the amount to be (or that was) sold
@return a SELL order