This is htree, a Go package that helps traverse, navigate, filter, and otherwise process trees of html.Node objects.
root, err := html.Parse(input) if err != nil { ... } body := htree.FindEl(root, func(n *html.Node) bool { return n.DataAtom == atom.Body }) content := htree.FindEl(body, func(n *html.Node) bool { return n.DataAtom == atom.Div && htree.ElClassContains(n, "content") }) ...etc...