code: func (trans *Transcription) Contents(client *messagebird.Client) (string, error) {
  	req, err := http.NewRequest(http.MethodGet, apiRoot+trans.links["file"], nil)
  	if err != nil {
  		return "", err
  	}
  	req.Header.Set("Accept", "text/plain")
  	req.Header.Set("Authorization", "AccessKey "+client.AccessKey)
  	req.Header.Set("User-Agent", "MessageBird/ApiClient/"+messagebird.ClientVersion+" Go/"+runtime.Version())
  
  	resp, err := client.HTTPClient.Do(req)
  	if err != nil {
  		return "", err
  	}
  	if resp.StatusCode != http.StatusOK {
  		return "", fmt.Errorf("bad HTTP status: %d", resp.StatusCode)
  	}
  
  	defer resp.Body.Close()
  	b, err := ioutil.ReadAll(resp.Body)
  	return string(b), err
  }
docs: // Contents gets the transcription file.
  //
  // This is a plain text file.