func (b *Builder) NewSegment() *Segment {
	seg := &Segment{tail: make([]*Node, MaxLevel+1),
		head: make([]*Node, MaxLevel+1), builder: b,
		rand: rand.New(rand.NewSource(int64(rand.Int()))),
	}

	seg.sts.IsLocal(true)
	return seg
}
func (b *Builder) NewSegment() *Segment {
	seg := &Segment{tail: make([]*Node, MaxLevel+1),
		head: make([]*Node, MaxLevel+1), builder: b,
		rand: rand.New(rand.NewSource(int64(rand.Int()))),
	}

	seg.sts.IsLocal(true)
	return seg
}
// NewSegment creates a new skiplist segment