code: func NewClient(cfg Config) (Client, error) {
  	u, err := url.Parse(cfg.Address)
  	if err != nil {
  		return nil, err
  	}
  	u.Path = strings.TrimRight(u.Path, "/")
  
  	return &httpClient{
  		endpoint: u,
  		client:   http.Client{Transport: cfg.roundTripper()},
  	}, nil
  }
docs: // NewClient returns a new Client.
  //
  // It is safe to use the returned Client from multiple goroutines.