取消订阅某一个策略

        Arguments:
            strategy_id {[type]} -- [description]

def unsubscribe_stratgy(self, strategy_id):
        """取消订阅某一个策略

        Arguments:
            strategy_id {[type]} -- [description]
        """

        today = datetime.date.today()
        order_id = str(uuid.uuid1())
        if strategy_id in self._subscribed_strategy.keys():
            self._subscribed_strategy[strategy_id]['status'] = 'canceled'

        self.coins_history.append(
            [0,
             strategy_id,
             str(today),
             0,
             order_id,
             'unsubscribe']
        )