func (s *Skiplist) NewUniIterator(reversed bool) *UniIterator {
	return &UniIterator{
		iter:     s.NewIterator(),
		reversed: reversed,
	}
}
func (s *Skiplist) NewUniIterator(reversed bool) *UniIterator {
	return &UniIterator{
		iter:     s.NewIterator(),
		reversed: reversed,
	}
}
// NewUniIterator returns a UniIterator.