func (s *Selection) AddNodes(nodes ...*html.Node) *Selection {
	return pushStack(s, appendWithoutDuplicates(s.Nodes, nodes))
}
AddNodes adds the specified nodes to those in the
current selection and returns a new Selection object.
package goquery
import (
	"github.com/andybalholm/cascadia"
	"golang.org/x/net/html"
)
func (s *Selection) Add(selector string) *Selection {
	return s.AddNodes(findWithMatcher([]*html.Node{s.document.rootNode}, cascadia.MustCompile(selector))...)
}
func (s *Selection) AddMatcher(m Matcher) *Selection {
	return s.AddNodes(findWithMatcher([]*html.Node{s.document.rootNode}, m)...)
}
func (s *Selection) AddSelection(sel *Selection) *Selection {
	if sel == nil {
		return s.AddNodes()
	}
	return s.AddNodes(sel.Nodes...)
}
func (s *Selection) Union(sel *Selection) *Selection {
	return s.AddSelection(sel)
}