code: func logPreviousSHAs(cb GitScannerFoundPointer, ref string, since time.Time) error {
  	logArgs := []string{
  		fmt.Sprintf("--since=%v", git.FormatGitDate(since)),
  	}
  	// Add standard search args to find lfs references
  	logArgs = append(logArgs, logLfsSearchArgs...)
  	// ending at ref
  	logArgs = append(logArgs, ref)
  
  	cmd, err := git.Log(logArgs...)
  	if err != nil {
  		return err
  	}
  
  	parseScannerLogOutput(cb, LogDiffDeletions, cmd)
  	return nil
  }
docs: // logPreviousVersions scans history for all previous versions of LFS pointers
  // from 'since' up to (but not including) the final state at ref