human
3. 卖出择时因子的实现
上面所有单子都没有成交的原因是没有卖出因子，下面首先实现类似买入策略的N日趋势突破策略AbuFactorSellBreak，当股价向下突破N日最低价格时卖出股票，即当天收盘价格低于N天内最低价格作为卖出信号，认为下跌趋势成立卖出股票："
Please write code following the instructions in jupyter notebook style.

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Write me a code to 3?
assistant
#Here is code to 3.

from abupy import AbuFactorSellXD, ESupportDirection

class AbuFactorSellBreak(AbuFactorSellXD):
    """示例继承AbuFactorBuyXD, 向下突破卖出择时因子"""
    def support_direction(self):
        """支持的方向，只支持正向"""
        return [ESupportDirection.DIRECTION_CAll.value]

    def fit_day(self, today, orders):
        """
        寻找向下突破作为策略卖出驱动event
        :param today: 当前驱动的交易日金融时间序列数据
        :param orders: 买入择时策略中生成的订单序列
        """
        # 今天的收盘价格达到xd天内最低价格则符合条件
        if today.close == self.xd_kl.close.min():
            for order in orders:
                self.sell_tomorrow(order)