code: func (e *Epoch) UnmarshalBinary(data []byte) error {
  	if len(data) != EpochLength {
  		return errors.New("Invalid data unmarshalling Epoch")
  	}
  	b := make([]byte, 8)
  	copy(b, data)
  	e.Level = b[7]
  	b[7] = 0
  	e.Time = binary.LittleEndian.Uint64(b)
  	return nil
  }
docs: // UnmarshalBinary implements the encoding.BinaryUnmarshaller interface