code: func (s *Scanner) NextObject(w io.Writer) (written int64, crc32 uint32, err error) {
  	s.pendingObject = nil
  	written, err = s.copyObject(w)
  
  	s.r.Flush()
  	crc32 = s.crc.Sum32()
  	s.crc.Reset()
  
  	return
  }
docs: // NextObject writes the content of the next object into the reader, returns
  // the number of bytes written, the CRC32 of the content and an error, if any