code: func newETCDClient() (coreDNSClient, error) {
  	cfg, err := getETCDConfig()
  	if err != nil {
  		return nil, err
  	}
  	c, err := etcdcv3.New(*cfg)
  	if err != nil {
  		return nil, err
  	}
  	return etcdClient{c, context.Background()}, nil
  }
docs: //newETCDClient is an etcd client constructor