private static AuthService ToAuthService(string consumerName, KeyElement consumerKey, KeyElement consumerSecret)
{
var authService = new AuthService(consumerName);
if (consumerKey != null)
authService.WithId(consumerKey.Name, consumerKey.Value);
if (consumerSecret != null)
authService.WithKey(consumerSecret.Name, consumerSecret.Value);
return authService;
}