def seconds(part = nil)
          # Table mapping
          h = {:weeks => WEEK, :days => DAY, :hours => HOUR, :minutes => MINUTE}

          if [:weeks, :days, :hours, :minutes].include? part
              __send__(part) * h[part]
          else
              @seconds
          end
      end
def seconds(part = nil)
          # Table mapping
          h = {:weeks => WEEK, :days => DAY, :hours => HOUR, :minutes => MINUTE}

          if [:weeks, :days, :hours, :minutes].include? part
              __send__(part) * h[part]
          else
              @seconds
          end
      end
Get the number of seconds of a given part, or simply just get the number of
 seconds.

 *Example*

     d = Duration.new(:weeks => 1, :days => 1, :hours => 1, :seconds => 30)
     => #<Duration: 1 week, 1 day, 1 hour and 30 seconds>
     d.seconds(:weeks)
     => 604800
     d.seconds(:days)
     => 86400
     d.seconds(:hours)
     => 3600
     d.seconds
     => 30