# File lib/crono/period.rb, line 14
    def next(since: nil)
      if @interval
        if since
          @next = @interval.next_within(since, @period)
        else
          return initial_next if @interval.within?(initial_next)
          @next = @interval.next_within(initial_next, @period)
        end
      else
        return initial_next unless since
        @next = @period.since(since)
      end

      @next = @next.beginning_of_week.advance(days: @on) if @on
      @next = @next.change(time_atts)
      return @next if @next.future?
      Time.now
    end