code: func (d *DNSProvider) login() error {
  	payload := &credentials{Customer: d.config.CustomerName, User: d.config.UserName, Pass: d.config.Password}
  	dynRes, err := d.sendRequest(http.MethodPost, "Session", payload)
  	if err != nil {
  		return err
  	}
  
  	var s session
  	err = json.Unmarshal(dynRes.Data, &s)
  	if err != nil {
  		return err
  	}
  
  	d.token = s.Token
  
  	return nil
  }
docs: // Starts a new Dyn API Session. Authenticates using customerName, userName,
  // password and receives a token to be used in for subsequent requests.