code: def get_rollback_status_reason(self, stack_name):
          
          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
docs: Process events and returns latest roll back reason