# File lib/libxml/document.rb, line 134
      def node_type_name
        case node_type
        when XML::Node::DOCUMENT_NODE
          'document_xml'
        when XML::Node::DOCB_DOCUMENT_NODE
          'document_docbook'
        when XML::Node::HTML_DOCUMENT_NODE
          'document_html'
        else
          raise(UnknownType, "Unknown node type: %n", node.node_type);
        end
      end