code: func (e *Epoch) MarshalBinary() (data []byte, err error) {
  	b := make([]byte, 8)
  	binary.LittleEndian.PutUint64(b[:], e.Time)
  	b[7] = e.Level
  	return b, nil
  }
docs: // MarshalBinary implements the encoding.BinaryMarshaller interface