code: func WriteDistributionProgress(cancelFunc func(), outStream io.Writer, progressChan <-chan progress.Progress) {
  	progressOutput := streamformatter.NewJSONProgressOutput(outStream, false)
  	operationCancelled := false
  
  	for prog := range progressChan {
  		if err := progressOutput.WriteProgress(prog); err != nil && !operationCancelled {
  			// don't log broken pipe errors as this is the normal case when a client aborts
  			if isBrokenPipe(err) {
  				logrus.Info("Pull session cancelled")
  			} else {
  				logrus.Errorf("error writing progress to client: %v", err)
  			}
  			cancelFunc()
  			operationCancelled = true
  			// Don't return, because we need to continue draining
  			// progressChan until it's closed to avoid a deadlock.
  		}
  	}
  }
docs: // WriteDistributionProgress is a helper for writing progress from chan to JSON
  // stream with an optional cancel function.