code: func TailFile(f *os.File, n int) ([][]byte, error) {
  	size, err := f.Seek(0, io.SeekEnd)
  	if err != nil {
  		return nil, err
  	}
  
  	rAt := io.NewSectionReader(f, 0, size)
  	r, nLines, err := NewTailReader(context.Background(), rAt, n)
  	if err != nil {
  		return nil, err
  	}
  
  	buf := make([][]byte, 0, nLines)
  	scanner := bufio.NewScanner(r)
  
  	for scanner.Scan() {
  		buf = append(buf, scanner.Bytes())
  	}
  	return buf, nil
  }
docs: //TailFile returns last n lines of the passed in file.