# File lib/execjs/encoding.rb, line 8
        def encode(string)
          if string.encoding.name == 'ASCII-8BIT'
            data = string.dup
            data.force_encoding('UTF-8')

            unless data.valid_encoding?
              raise ::Encoding::UndefinedConversionError, "Could not encode ASCII-8BIT data #{string.dump} as UTF-8"
            end
          else
            data = string.encode('UTF-8')
          end
          data
        end