UTF-8 compatible String ranges in Ruby (See related posts)

class String
        def [] (*params)
                if params.all? { |p| Integer===p } ||
                   params.size==1 && Range===params[0]
                        res = self.unpack("U*").[](*params)
                        res = [res] unless Array===res
                        return res.pack("U*")
                end
                super
        end
end