# File lib/ri_cal/property_value/recurrence_rule.rb, line 135
      def to_ical
        result = ["FREQ=#{freq}"]
        result << "INTERVAL=#{interval}" unless interval == 1
        result << "COUNT=#{count}" if count
        result << "UNTIL=#{self.until.value}" if self.until
        %w{bysecond byminute byhour byday bymonthday byyearday byweekno bymonth bysetpos}.each do |by_part|
          val = by_list[by_part.to_sym]
          result << "#{by_part.upcase}=#{[val].flatten.join(',')}" if val
        end
        result << "WKST=#{wkst}" unless wkst == "MO"
        result.join(";")
      end