code: func (d *DUIDUUID) MarshalBinary() ([]byte, error) {
  	//  2 bytes: DUID type
  	// 16 bytes: UUID
  	b := buffer.New(nil)
  
  	b.Write16(uint16(d.Type))
  	b.WriteBytes(d.UUID[:])
  
  	return b.Data(), nil
  }
docs: // MarshalBinary allocates a byte slice containing the data from a DUIDUUID.