code: func (callflow *CallFlow) Update(client *messagebird.Client) error {
  	var data struct {
  		Data []CallFlow `json:"data"`
  	}
  	if err := client.Request(&data, http.MethodPut, apiRoot+"/call-flows/"+callflow.ID, callflow); err != nil {
  		return err
  	}
  	*callflow = data.Data[0]
  	return nil
  }
docs: // Update updates the call flow by overwriting it.
  //
  // An error is returned if no such call flow exists or is accessible.