selectable.go
func (s *selectable) FindByClass(text string) *Selection {
	return newSelection(s.session, s.selectors.Append(target.Class, text).Single())
}
func (s *selectable) FindByClass(text string) *Selection {
	return newSelection(s.session, s.selectors.Append(target.Class, text).Single())
}
// FindByClass finds exactly one element with a given CSS class.