diff --git a/server.py b/server.py
index eeb8920..3dc46cb 100644
--- a/server.py
+++ b/server.py
@@ -17,79 +17,79 @@ from flask_babel import Babel, _
 from flask_simple_csrf import CSRF
 
 
-static_dir = str(os.path.abspath(os.path.join(
-    __file__, "..", 'assets')))
-app = Flask(__name__, static_folder=static_dir,
-            static_url_path="", template_folder=static_dir)
-app.config.from_pyfile('settings.py')
-stripe.api_key = app.config['STRIPE_SECRET_KEY']
-CSRF = CSRF(config={
-    'SECRET_CSRF_KEY': app.config['SECRET_CSRF_KEY']
-})
+static_dir = str(os.path.abspath(os.path.join(__file__, "..", "assets")))
+app = Flask(
+    __name__, static_folder=static_dir, static_url_path="", template_folder=static_dir
+)
+app.config.from_pyfile("settings.py")
+stripe.api_key = app.config["STRIPE_SECRET_KEY"]
+CSRF = CSRF(config={"SECRET_CSRF_KEY": app.config["SECRET_CSRF_KEY"]})
 app = CSRF.init_app(app)
 babel = Babel(app)
 
+
 @app.before_request
 def before_request():
-    if 'CSRF_TOKEN' not in session or 'USER_CSRF' not in session:
-        session['USER_CSRF'] = ''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(64))
-        session['CSRF_TOKEN'] = CSRF.create(session['USER_CSRF'])
+    if "CSRF_TOKEN" not in session or "USER_CSRF" not in session:
+        session["USER_CSRF"] = "".join(
+            random.SystemRandom().choice(string.ascii_uppercase + string.digits)
+            for _ in range(64)
+        )
+        session["CSRF_TOKEN"] = CSRF.create(session["USER_CSRF"])
+
 
 @babel.localeselector
 def get_locale():
-    return 'fr' #request.accept_languages.best_match(app.config['LANGUAGES'])
+    return "fr"  # request.accept_languages.best_match(app.config['LANGUAGES'])
 
-@app.route('/', methods=['GET'])
+
+@app.route("/", methods=["GET"])
 def get_index():
-    return render_template('index.html', **app.config['CUSTOM'],
-                           csrf=session['USER_CSRF'])
+    return render_template(
+        "index.html", **app.config["CUSTOM"], csrf=session["USER_CSRF"]
+    )
 
 
-@app.route('/success', methods=['GET'])
+@app.route("/success", methods=["GET"])
 def get_success():
-    return render_template('success.html', **app.config['CUSTOM'])
+    return render_template("success.html", **app.config["CUSTOM"])
 
 
-@app.route('/canceled', methods=['GET'])
+@app.route("/canceled", methods=["GET"])
 def get_canceled():
-    return render_template('canceled.html', **app.config['CUSTOM'])
+    return render_template("canceled.html", **app.config["CUSTOM"])
 
 
-@app.route('/create-checkout-session', methods=['POST'])
+@app.route("/create-checkout-session", methods=["POST"])
 def create_checkout_session():
     data = json.loads(request.data)
-    domain_url = app.config['DOMAIN']
+    domain_url = app.config["DOMAIN"]
     try:
-        donation = app.config['DONATION']
-        currencies = [iso for iso, symbol in app.config['CUSTOM']['currencies']]
-        if CSRF.verify(data['user_csrf'], session['CSRF_TOKEN']) is False or \
-           data['frequency'] not in ['recuring', 'one_time'] or \
-           data['currency'] not in currencies or \
-           int(data['quantity']) <= 0:
+        donation = app.config["DONATION"]
+        currencies = [iso for iso, symbol in app.config["CUSTOM"]["currencies"]]
+        if (
+            CSRF.verify(data["user_csrf"], session["CSRF_TOKEN"]) is False
+            or data["frequency"] not in ["recuring", "one_time"]
+            or data["currency"] not in currencies
+            or int(data["quantity"]) <= 0
+        ):
             return jsonify(error="Bad value"), 400
 
         # Create new Checkout Session for the order
-        price = donation[data['frequency']][data['currency']]
-        mode = "payment" if data['frequency'] == 'one_time' else "subscription"
+        price = donation[data["frequency"]][data["currency"]]
+        mode = "payment" if data["frequency"] == "one_time" else "subscription"
 
         checkout_session = stripe.checkout.Session.create(
-            success_url=domain_url +
-            "/success?session_id={CHECKOUT_SESSION_ID}",
+            success_url=domain_url + "/success?session_id={CHECKOUT_SESSION_ID}",
             cancel_url=domain_url + "/canceled",
-            payment_method_types= ["card"],
+            payment_method_types=["card"],
             mode=mode,
-            line_items=[
-                {
-                    "price": price,
-                    "quantity": data['quantity']
-                }
-            ]
+            line_items=[{"price": price, "quantity": data["quantity"]}],
         )
-        return jsonify({'sessionId': checkout_session['id']})
+        return jsonify({"sessionId": checkout_session["id"]})
     except Exception as e:
         return jsonify(error=str(e)), 403
 
 
-
-if __name__ == '__main__':
-    app.run(port=app.config['PORT'], debug=app.debug)
+if __name__ == "__main__":
+    app.run(port=app.config["PORT"], debug=app.debug)