func indexInSlice(slice []*html.Node, node *html.Node) int {
	if node != nil {
		for i, n := range slice {
			if n == node {
				return i
			}
		}
	}
	return -1
}
Returns the index of the target node in the slice, or -1.
package goquery
import (
	"bytes"
	"golang.org/x/net/html"
)
var nodeNames = []string{
	html.ErrorNode:    "#error",
	html.TextNode:     "#text",
	html.DocumentNode: "#document",
	html.CommentNode:  "#comment",
}
func NodeName(s *Selection) string {
	if s.Length() == 0 {
		return ""
	}
	switch n := s.Get(0); n.Type {
	case html.ElementNode, html.DoctypeNode:
		return n.Data
	default:
		if n.Type >= 0 && int(n.Type) < len(nodeNames) {
			return nodeNames[n.Type]
		}
		return ""
	}
}
func OuterHtml(s *Selection) (string, error) {
	var buf bytes.Buffer
	if s.Length() == 0 {
		return "", nil
	}
	n := s.Get(0)
	if err := html.Render(&buf, n); err != nil {
		return "", err
	}
	return buf.String(), nil
}
func getChildren(n *html.Node) (result []*html.Node) {
	for c := n.FirstChild; c != nil; c = c.NextSibling {
		result = append(result, c)
	}
	return result
}
func sliceContains(container []*html.Node, contained *html.Node) bool {
	for _, n := range container {
		if nodeContains(n, contained) {
			return true
		}
	}
	return false
}
func nodeContains(container *html.Node, contained *html.Node) bool {
	for contained = contained.Parent; contained != nil; contained = contained.Parent {
		if container == contained {
			return true
		}
	}
	return false
}
func isInSlice(slice []*html.Node, node *html.Node) bool {
	return indexInSlice(slice, node) > -1
}