code: func doPurge(cmdline []string) {
  	var (
  		store = flag.String("store", "", `Destination from where to purge archives (usually "gethstore/builds")`)
  		limit = flag.Int("days", 30, `Age threshold above which to delete unstable archives`)
  	)
  	flag.CommandLine.Parse(cmdline)
  
  	if env := build.Env(); !env.IsCronJob {
  		log.Printf("skipping because not a cron job")
  		os.Exit(0)
  	}
  	// Create the azure authentication and list the current archives
  	auth := build.AzureBlobstoreConfig{
  		Account:   strings.Split(*store, "/")[0],
  		Token:     os.Getenv("AZURE_BLOBSTORE_TOKEN"),
  		Container: strings.SplitN(*store, "/", 2)[1],
  	}
  	blobs, err := build.AzureBlobstoreList(auth)
  	if err != nil {
  		log.Fatal(err)
  	}
  	// Iterate over the blobs, collect and sort all unstable builds
  	for i := 0; i < len(blobs); i++ {
  		if !strings.Contains(blobs[i].Name, "unstable") {
  			blobs = append(blobs[:i], blobs[i+1:]...)
  			i--
  		}
  	}
  	for i := 0; i < len(blobs); i++ {
  		for j := i + 1; j < len(blobs); j++ {
  			if blobs[i].Properties.LastModified.After(blobs[j].Properties.LastModified) {
  				blobs[i], blobs[j] = blobs[j], blobs[i]
  			}
  		}
  	}
  	// Filter out all archives more recent that the given threshold
  	for i, blob := range blobs {
  		if time.Since(blob.Properties.LastModified) < time.Duration(*limit)*24*time.Hour {
  			blobs = blobs[:i]
  			break
  		}
  	}
  	// Delete all marked as such and return
  	if err := build.AzureBlobstoreDelete(auth, blobs); err != nil {
  		log.Fatal(err)
  	}
  }
docs: // Binary distribution cleanups