code: def past_datetime(self, start_date='-30d', tzinfo=None):
          
          return self.date_time_between(
              start_date=start_date, end_date='-1s', tzinfo=tzinfo,
          )
docs: Get a DateTime object based on a random date between a given date and 1
          second ago.
          Accepts date strings that can be recognized by strtotime().
  
          :param start_date Defaults to "-30d"
          :param tzinfo: timezone, instance of datetime.tzinfo subclass
          :example DateTime('1999-02-02 11:42:52')
          :return DateTime