# File lib/ice_cube/validations/day.rb, line 50
      def build_ical(builder)
        ical_day = IcalBuilder.fixnum_to_ical_day(day)
        # Only add if there aren't others from day_of_week that override
        if builder['BYDAY'].none? { |b| b.end_with?(ical_day) }
          builder['BYDAY'] << ical_day
        end
      end