How to use the deployfish.aws.appscaling.ScalingPolicy function in deployfish

def needs_update(self):
        """
        If our desired scaling policy or associated CloudWatch alarm is
        different than what actually exists in AWS, return ``True``, else return
        ``False``.

        :rtype: boolean
        """
        if self == ScalingPolicy(self.serviceName, self.clusterName, aws=self.__aws_scaling_policy):
            if self.alarm.needs_update():
                return True
            return False
        return True

def from_yaml(self, yml):
        """
        Load our configuration from the config read from ``deployfish.yml``.

        :param yml: a application-scaling level entry from the ``deployfish.yml`` file
        :type yml: dict
        """
        if yml:
            self.__yml = yml
            self.MinCapacity = yml['min_capacity']
            self.MaxCapacity = yml['max_capacity']
            self._RoleARN = yml['role_arn']
            self.policies['scale-up'] = ScalingPolicy(self.serviceName, self.clusterName, yml['scale-up'])
            self.policies['scale-down'] = ScalingPolicy(self.serviceName, self.clusterName, yml['scale-down'])

def update(self):
        """
        If our desired scaling policy or associated CloudWatch alarm is
        different than what actually exists in AWS, delete them and recreate
        them with the config we want.
        """
        if self != ScalingPolicy(self.serviceName, self.clusterName, aws=self.__aws_scaling_policy):
            # The scaling policy itself needs updating
            self.delete()
            self.create()
        else:
            # The scaling policy doesn't need updating, but maybe the alarm does
            self.alarm.update()