# File lib/execjs/external_runtime.rb, line 78
          def encode_unicode_codepoints(str)
            str.gsub(/([\xC0-\xDF][\x80-\xBF]|
                       [\xE0-\xEF][\x80-\xBF]{2}|
                       [\xF0-\xF7][\x80-\xBF]{3})+/nx) do |ch|
              "\\u%04x" % ch.unpack("U*")
            end
          end