code: def get_success_url(self):
          
          url_val = 'fullcalendar' if USE_FULLCALENDAR else 'day_calendar'
          next_url = self.kwargs.get('next') or reverse(url_val, args=[self.object.calendar.slug])
          next_url = get_next_url(self.request, next_url)
          return next_url
docs: After the event is deleted there are three options for redirect, tried in
          this order:
          # Try to find a 'next' GET variable
          # If the key word argument redirect is set
          # Lastly redirect to the event detail of the recently create event