<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def delete_policy(self, policy_name, autoscale_group=None):
 """ Delete a policy. :type policy_name: str :param policy_name: The name or ARN of the policy to delete. :type autoscale_group: str :param autoscale_group: The name of the autoscale group. """

        params = {'PolicyName': policy_name}
        if autoscale_group:
            params['AutoScalingGroupName'] = autoscale_group
        return self.get_status('DeletePolicy', params)