'Adds an alarm action, represented as an SNS topic, to this alarm.
What do do when alarm is triggered.
:type action_arn: str
:param action_arn: SNS topics to which notification should be
sent if the alarm goes to state ALARM.'

def add_alarm_action(self, action_arn=None):

    if (not action_arn):
        return
    self.actions_enabled = 'true'
    self.alarm_actions.append(action_arn)
