code: func (d *DUIDEN) MarshalBinary() ([]byte, error) {
  	// 2 bytes: DUID type
  	// 4 bytes: enterprise number
  	// N bytes: identifier
  	b := buffer.New(nil)
  
  	b.Write16(uint16(d.Type))
  	b.Write32(d.EnterpriseNumber)
  	b.WriteBytes(d.Identifier)
  
  	return b.Data(), nil
  }
docs: // MarshalBinary allocates a byte slice containing the data from a DUIDEN.