normalize

# File activesupport/lib/active_support/duration/iso8601_serializer.rb, line 38
        def normalize
          parts = @duration.parts.each_with_object(Hash.new(0)) do |(k, v), p|
            p[k] += v  unless v.zero?
          end

          # Convert weeks to days and remove weeks if mixed with date parts
          if week_mixed_with_date?(parts)
            parts[:days] += parts.delete(:weeks) * SECONDS_PER_WEEK / SECONDS_PER_DAY
          end

          parts
        end