def add_recurrence_time(time)
      return if time.nil?
      rule = SingleOccurrenceRule.new(time)
      add_recurrence_rule rule
      time
    end
def add_recurrence_time(time)
      return if time.nil?
      rule = SingleOccurrenceRule.new(time)
      add_recurrence_rule rule
      time
    end
Add a recurrence time to the schedule