code: func NewScanner(r io.Reader) *Scanner {
  	_, ok := r.(io.ReadSeeker)
  
  	crc := crc32.NewIEEE()
  	return &Scanner{
  		r:          newScannerReader(r, crc),
  		crc:        crc,
  		IsSeekable: ok,
  	}
  }
docs: // NewScanner returns a new Scanner based on a reader, if the given reader
  // implements io.ReadSeeker the Scanner will be also Seekable