code: func (c *Client) GetSessions(namespace string) ([]session.Session, error) {
  	if namespace == "" {
  		return nil, trace.BadParameter(MissingNamespaceError)
  	}
  	out, err := c.Get(c.Endpoint("namespaces", namespace, "sessions"), url.Values{})
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	var sessions []session.Session
  	if err := json.Unmarshal(out.Bytes(), &sessions); err != nil {
  		return nil, err
  	}
  	return sessions, nil
  }
docs: // GetSessions returns a list of active sessions in the cluster
  // as reported by auth server