& (Nokogiri::XML::NodeSet)

    /*
     * call-seq:
     *  &(node_set)
     *
     * Set Intersection — Returns a new NodeSet containing nodes common to the two NodeSets.
     */
    static VALUE intersection(VALUE self, VALUE rb_other)
    {
      xmlNodeSetPtr node_set;
      xmlNodeSetPtr other;

      if(! rb_funcall(rb_other, rb_intern("is_a?"), 1, cNokogiriXmlNodeSet))
        rb_raise(rb_eArgError, "node_set must be a Nokogiri::XML::NodeSet");

      Data_Get_Struct(self, xmlNodeSet, node_set);
      Data_Get_Struct(rb_other, xmlNodeSet, other);

      return Nokogiri_wrap_xml_node_set(xmlXPathIntersection(node_set, other));
    }