code: def _init_date_range(self, start_date=None, end_date=None):
          
          self.end_date = end_date
          self.start_date = start_date
          if self.end_date is None:
              today = now_utc().date()
              end_date = self.event.end_dt.date()
              self.end_date = end_date if end_date < today else today
          if self.start_date is None:
              self.start_date = self.end_date - timedelta(days=ReportBase.default_report_interval)
docs: Set date range defaults if no dates are passed