class String
      def reverse_caps
        self.reverse.upcase
      end
    end

    class Array
      def shuffle
        self.sort_by { rand }
      end
    end

    class Fixnum
      def cubed
        self**3
      end
    end

    "abcde".reverse_caps         # "EDCBA"
    5.cubed                      # 125
    [1,2,3,4,5].shuffle          # [5,1,3,4,2]