code: func Sha1Sum(path string) string {
  	f, err := os.Open(path)
  	Expect(err).ToNot(HaveOccurred())
  	defer f.Close()
  
  	hash := sha1.New()
  	_, err = io.Copy(hash, f)
  	Expect(err).ToNot(HaveOccurred())
  
  	return fmt.Sprintf("%x", hash.Sum(nil))
  }
docs: // Sha1Sum calculates the SHA1 sum of a file.