    # File lib/nokogiri/xml/node.rb, line 549
          def to_xhtml options = {}
            # FIXME: this is a hack around broken libxml versions
            return dump_html if %w[2 6] === LIBXML_VERSION.split('.')[0..1]

            options[:save_with] ||= SaveOptions::FORMAT |
                                    SaveOptions::NO_DECLARATION |
                                    SaveOptions::NO_EMPTY_TAGS |
                                    SaveOptions::AS_XHTML

            serialize(options)
          end