private void OnSignedIn(JsonValue data)
        {
            if (SignedIn != null)
            {
                var json = data.AsDynamic();

                var response = new AccessTokenResponse
                {
                    AccessToken = json.access_token,
                    ExpiresIn = json.expires_in,
                    TokenType = json.token_type
                };

                SignedIn(this, new SignedInEventArgs { Response = response });
            }
        }