def seconds
      @seconds ||= duration.split(':').collect(&:to_i).reverse.
        inject([1, 0]) { |(m, sum), i| [m * 60, sum + i * m] }.last
    end
def seconds
      @seconds ||= duration.split(':').collect(&:to_i).reverse.
        inject([1, 0]) { |(m, sum), i| [m * 60, sum + i * m] }.last
    end
The number of seconds described by the duration. E.g., if the
 duration were `"1:02:42"`, this method would return `3762`.

 @return [Fixnum]