inspect

# File activesupport/lib/active_support/duration.rb, line 445
    def inspect # :nodoc:
      return "#{value} seconds" if @parts.empty?

      @parts.
        sort_by { |unit,  _ | PARTS.index(unit) }.
        map     { |unit, val| "#{val} #{val == 1 ? unit.to_s.chop : unit.to_s}" }.
        to_sentence(locale: false)
    end