code: func ByTag(a atom.Atom) Matcher {
  	return func(node *html.Node) bool { return node.DataAtom == a }
  }
docs: // ByTag returns a Matcher which matches all nodes of the provided tag type.
  //
  //     root, err := html.Parse(resp.Body)
  //     if err != nil {
  //         // handle error
  //     }
  //     title, ok := scrape.Find(root, scrape.ByTag(atom.Title))