new (Nokogiri::XML::XPathContext)

    /*
     * call-seq:
     *  new(node)
     *
     * Create a new XPathContext with +node+ as the reference point.
     */
    static VALUE new(VALUE klass, VALUE nodeobj)
    {
      xmlXPathInit();

      xmlNodePtr node ;
      Data_Get_Struct(nodeobj, xmlNode, node);

      xmlXPathContextPtr ctx = xmlXPathNewContext(node->doc);
      ctx->node = node;
      VALUE self = Data_Wrap_Struct(klass, 0, deallocate, ctx);
      //rb_iv_set(self, "@xpath_handler", Qnil);
      return self;
    }