def bookable_must_be_bookable
        if bookable.present? && !bookable.class.bookable?
          errors.add(:bookable, T.er('booking.bookable_must_be_bookable', model: bookable.class.to_s))
        end
      end
def bookable_must_be_bookable
        if bookable.present? && !bookable.class.bookable?
          errors.add(:bookable, T.er('booking.bookable_must_be_bookable', model: bookable.class.to_s))
        end
      end
Validation method. Check if the bookable resource is actually bookable