func (g *Generator) Next() uint64 {
	suffix := atomic.AddUint64(&g.suffix, 1)
	id := g.prefix | lowbit(suffix, suffixLen)
	return id
}
func (g *Generator) Next() uint64 {
	suffix := atomic.AddUint64(&g.suffix, 1)
	id := g.prefix | lowbit(suffix, suffixLen)
	return id
}
// Next generates a id that is unique.