write_xhtml_to (Nokogiri::XML::Node)

    # File lib/nokogiri/xml/node.rb, line 611
          def write_xhtml_to io, options = {}
            # FIXME: this is a hack around broken libxml versions
            return (io << 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
            write_to io, options
          end