code: def get_next_notif_time(self, t_wished, status, creation_time, interval, escal_period):
          short_states = {u'WARNING': 'w', u'UNKNOWN': 'u', u'CRITICAL': 'c',
                          u'RECOVERY': 'r', u'FLAPPING': 'f', u'DOWNTIME': 's',
                          u'DOWN': 'd', u'UNREACHABLE': 'u', u'OK': 'o', u'UP': 'o'}
          if not self.time_based:
              return None
          if status in short_states and short_states[status] not in self.escalation_options:
              return None
          start = self.first_notification_time * interval + creation_time
          if start > t_wished:
              return None
          if escal_period is not None and not escal_period.is_time_valid(start):
              return None
          return start