func (s *Selection) FindSelection(sel *Selection) *Selection {
	if sel == nil {
		return pushStack(s, nil)
	}
	return s.FindNodes(sel.Nodes...)
}
FindSelection gets the descendants of each element in the current
Selection, filtered by a Selection. It returns a new Selection object
containing these matched elements.
package goquery
import (
	"github.com/andybalholm/cascadia"
	"golang.org/x/net/html"
)
type siblingType int
const (
	siblingPrevUntil siblingType = iota - 3
	siblingPrevAll
	siblingPrev
	siblingAll
	siblingNext
	siblingNextAll
	siblingNextUntil
	siblingAllIncludingNonElements
)
func (s *Selection) Find(selector string) *Selection {
	return pushStack(s, findWithMatcher(s.Nodes, cascadia.MustCompile(selector)))
}
func (s *Selection) FindMatcher(m Matcher) *Selection {
	return pushStack(s, findWithMatcher(s.Nodes, m))
}