code: func deserializeToken(token string) (*messages.DelegationToken, error) {
  	blob, err := base64.RawURLEncoding.DecodeString(token)
  	if err != nil {
  		return nil, err
  	}
  	if len(blob) > maxTokenSize {
  		return nil, fmt.Errorf("the delegation token is too big (%d bytes)", len(blob))
  	}
  	tok := &messages.DelegationToken{}
  	if err = proto.Unmarshal(blob, tok); err != nil {
  		return nil, err
  	}
  	return tok, nil
  }
docs: // deserializeToken deserializes DelegationToken proto message.