code: func (o *OAuthSession) CodeAuth(code string) error {
  	t, err := o.OAuthConfig.Exchange(o.ctx, code)
  	if err != nil {
  		return err
  	}
  	o.Client = o.OAuthConfig.Client(o.ctx, t)
  	return nil
  }
docs: // CodeAuth creates and sets a token using an authentication code returned from AuthCodeURL.