code: func (c *Client) GetSession(namespace string, id session.ID) (*session.Session, error) {
  	if namespace == "" {
  		return nil, trace.BadParameter(MissingNamespaceError)
  	}
  	// saving extra round-trip
  	if err := id.Check(); err != nil {
  		return nil, trace.Wrap(err)
  	}
  	out, err := c.Get(c.Endpoint("namespaces", namespace, "sessions", string(id)), url.Values{})
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	var sess *session.Session
  	if err := json.Unmarshal(out.Bytes(), &sess); err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return sess, nil
  }
docs: // GetSession returns a session by ID