code: func (ns Seq) Expand() []byte {
  	s := make([]byte, ns.Length)
  	for i := range s {
  		if i&1 == 0 {
  			s[i] = n16TableRev[ns.Seq[i>>1]>>4]
  		} else {
  			s[i] = n16TableRev[ns.Seq[i>>1]&0xf]
  		}
  	}
  
  	return s
  }
docs: // Expand returns the byte encoded form of the receiver.