code: def is_flapping(self, alert, window=1800, count=2):
          
          select = """
              SELECT COUNT(*)
                FROM alerts, unnest(history) h
               WHERE environment=%(environment)s
                 AND resource=%(resource)s
                 AND h.event=%(event)s
                 AND h.update_time > (NOW() at time zone 'utc' - INTERVAL '{window} seconds')
                 AND h.type='severity'
                 AND {customer}
          """.format(window=window, customer='customer=%(customer)s' if alert.customer else 'customer IS NULL')
          return self._fetchone(select, vars(alert)).count > count
docs: Return true if alert severity has changed more than X times in Y seconds