def sell(self, security, price=0, amount=0, volume=0, entrust_prop=0):
        """卖出股票
        :param security: 股票代码
        :param price: 卖出价格
        :param amount: 卖出股数
        :param volume: 卖出总金额 由 volume / price 取整， 若指定 price 则此参数无效
        :param entrust_prop:
        """
        return self._trade(security, price, amount, volume, "sell")