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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_rollback_status_reason(self, stack_name):
 """Process events and returns latest roll back reason"""

        event = next((item for item in self.get_events(stack_name,
                      False) if item["ResourceStatus"] ==
                      "UPDATE_ROLLBACK_IN_PROGRESS"), None)
        if event:
            reason = event["ResourceStatusReason"]
            return reason
        else:
            event = next((item for item in self.get_events(stack_name)
                          if item["ResourceStatus"] ==
                          "ROLLBACK_IN_PROGRESS"), None)
            reason = event["ResourceStatusReason"]
            return reason