code: func ReadUint64(r io.Reader) (uint64, error) {
  	var v uint64
  	if err := binary.Read(r, binary.BigEndian, &v); err != nil {
  		return 0, err
  	}
  
  	return v, nil
  }
docs: // ReadUint64 reads 8 bytes and returns them as a BigEndian uint32