code: func (tc *TeleportClient) ListNodes(ctx context.Context) ([]services.Server, error) {
  	var err error
  	// userhost is specified? that must be labels
  	if tc.Host != "" {
  		tc.Labels, err = ParseLabelSpec(tc.Host)
  		if err != nil {
  			return nil, trace.Wrap(err)
  		}
  	}
  
  	// connect to the proxy and ask it to return a full list of servers
  	proxyClient, err := tc.ConnectToProxy(ctx)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	defer proxyClient.Close()
  
  	return proxyClient.FindServersByLabels(ctx, tc.Namespace, tc.Labels)
  }
docs: // ListNodes returns a list of nodes connected to a proxy