code: func (a *Agent) updateTTL(checkID, note, status string) error {
  	switch status {
  	case "pass":
  	case "warn":
  	case "fail":
  	default:
  		return fmt.Errorf("Invalid status: %s", status)
  	}
  	endpoint := fmt.Sprintf("/v1/agent/check/%s/%s", status, checkID)
  	r := a.c.newRequest("PUT", endpoint)
  	r.params.Set("note", note)
  	_, resp, err := requireOK(a.c.doRequest(r))
  	if err != nil {
  		return err
  	}
  	resp.Body.Close()
  	return nil
  }
docs: // updateTTL is used to update the TTL of a check. This is the internal
  // method that uses the old API that's present in Consul versions prior to
  // 0.6.4. Since Consul didn't have an analogous "update" API before it seemed
  // ok to break this (former) UpdateTTL in favor of the new UpdateTTL below,
  // but keep the old Pass/Warn/Fail methods using the old API under the hood.
  //
  // DEPRECATION NOTICE: This interface is deprecated in favor of UpdateTTL().
  // The client interface will be removed in 0.8 and the server endpoints will
  // be removed in 0.9.