code: func (z *nstate) enc() string {
  	var buf []byte
  	var v [10]byte
  	last := ^uint32(0)
  	n := binary.PutUvarint(v[:], uint64(z.partial))
  	buf = append(buf, v[:n]...)
  	n = binary.PutUvarint(v[:], uint64(z.flag))
  	buf = append(buf, v[:n]...)
  	dense := z.q.Dense()
  	ids := make([]int, 0, len(dense))
  	for _, id := range z.q.Dense() {
  		ids = append(ids, int(id))
  	}
  	sort.Ints(ids)
  	for _, id := range ids {
  		n := binary.PutUvarint(v[:], uint64(uint32(id)-last))
  		buf = append(buf, v[:n]...)
  		last = uint32(id)
  	}
  	return string(buf)
  }
docs: // enc encodes z as a string.