code: func (im *imp) doUserAPI(ctx context.Context, accessToken string, result interface{}, apiPath string, keyval ...string) error {
  	form := url.Values{}
  	form.Set("oauth_token", accessToken)
  	return im.doAPI(ctx, form, result, apiPath, keyval...)
  }
docs: // doUserAPI makes requests to the Foursquare API with a user token.
  // https://developer.foursquare.com/overview/auth#requests