code: func Dial(auth aws.Auth) (*Conn, error) {
  	buck := fmt.Sprintf("%s-com-haystacksoftware-arq", strings.ToLower(auth.AccessKey))
  	b := s3.New(auth, aws.USEast).Bucket(buck)
  	c := &Conn{
  		b:     b,
  		cache: filepath.Join(cachedir(), buck),
  	}
  	if runtime.GOOS == "darwin" {
  		c.altCache = filepath.Join(os.Getenv("HOME"), "Library/Arq/Cache.noindex/"+buck)
  	}
  
  	// Check that the bucket works by listing computers (relatively cheap).
  	if _, err := c.list("", "/", 10); err != nil {
  		return nil, err
  	}
  
  	// Create S3 lookaside cache directory.
  
  	return c, nil
  }
docs: // Dial establishes a connection to an S3 server holding Arq backups.