code: func (c *Parser) IDnSize() ([4]byte, uint32, error) {
  	var ID [4]byte
  	var blockSize uint32
  	if err := binary.Read(c.r, binary.BigEndian, &ID); err != nil {
  		return ID, blockSize, err
  	}
  	if err := binary.Read(c.r, binary.LittleEndian, &blockSize); err != err {
  		return ID, blockSize, err
  	}
  	return ID, blockSize, nil
  }
docs: // IDnSize returns the next ID + block size