public void Execute(IOAuth2SignInSettings signInSettings)
        {
            var authenticated = false;

            _proxy.Process(signInSettings, response =>
            {
                // TODO -- Keep the access token (response.AccessToken)
                _session.MarkAuthenticated(response.Email);
                _handlers.Success(response);

                authenticated = true;
            });

            if (!authenticated)
            {
                _handlers.Failure();
            }
        }