code: func blobHash(path string, commit *object.Commit) (hash plumbing.Hash, found bool) {
  	file, err := commit.File(path)
  	if err != nil {
  		var empty plumbing.Hash
  		return empty, found
  	}
  	return file.Hash, true
  }
docs: // blobHash returns the hash of a path in a commit