code: func NewHTTPMonitor(ctx context.Context, client *http.Client, endpoint *url.URL) (Monitor, error) {
  	return &httpMonitor{
  		client:   client,
  		endpoint: endpoint,
  	}, nil
  }
docs: // NewHTTPMonitor creates a new Monitor object that sends metric to an HTTP
  // (or HTTPS) endpoint.  The http client should be authenticated as required.