skl/skl.go
func (s *Iterator) Next() {
	y.AssertTrue(s.Valid())
	s.n = s.list.getNext(s.n, 0)
}
func (s *Iterator) Next() {
	y.AssertTrue(s.Valid())
	s.n = s.list.getNext(s.n, 0)
}
// Next advances to the next position.