code: func (d *VaultAgentTokenQuery) Fetch(clients *ClientSet, opts *QueryOptions) (interface{}, *ResponseMetadata, error) {
  	log.Printf("[TRACE] %s: READ %s", d, d.path)
  
  	select {
  	case <-d.stopCh:
  		log.Printf("[TRACE] %s: stopped", d)
  		return "", nil, ErrStopped
  	case r := <-d.watch(d.stat):
  		if r.err != nil {
  			return "", nil, errors.Wrap(r.err, d.String())
  		}
  
  		log.Printf("[TRACE] %s: reported change", d)
  
  		token, err := ioutil.ReadFile(d.path)
  		if err != nil {
  			return "", nil, errors.Wrap(err, d.String())
  		}
  
  		d.stat = r.stat
  		clients.Vault().SetToken(strings.TrimSpace(string(token)))
  	}
  
  	return respWithMetadata("")
  }
docs: // Fetch retrieves this dependency and returns the result or any errors that
  // occur in the process.