How Do I Fix Errors Arising from working with python sessions and flask_session

Question

C:\pythonapp\flask-sess>flask run

• Serving Flask app 'app3.py' (lazy loading)
• Environment: production WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
• Debug mode: off
• Running on http://127.0.0.1:5000/ (Press CTRL+C to quit) [2022-04-25 16:45:25,032] ERROR in app: Exception on / [GET] Traceback (most recent call last): File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 2077, in wsgi_app response = self.full_dispatch_request() File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1525, in full_dispatch_request rv = self.handle_user_exception(e) File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1523, in full_dispatch_request rv = self.dispatch_request() File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1509, in dispatch_request return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args) File "C:\pythonapp\flask-sess\app3.py", line 15, in index session["notes"] = [] File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\sessions.py", line 97, in _fail raise RuntimeError( RuntimeError: The session is unavailable because no secret key was set. Set the secret_key on the application to something unique and secret. 127.0.0.1 - - [25/Apr/2022 16:45:25] "GET / HTTP/1.1" 500 - [2022-04-25 16:45:25,608] ERROR in app: Exception on / [GET] Traceback (most recent call last): File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 2077, in wsgi_app response = self.full_dispatch_request() File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1525, in full_dispatch_request rv = self.handle_user_exception(e) File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1523, in full_dispatch_request rv = self.dispatch_request() File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1509, in dispatch_request return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args) File "C:\pythonapp\flask-sess\app3.py", line 15, in index session["notes"] = [] File "C:\Users\christ\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\sessions.py", line 97, in _fail raise RuntimeError( RuntimeError: The session is unavailable because no secret key was set. Set the secret_key on the application to something unique and secret. 127.0.0.1 - - [25/Apr/2022 16:45:25] "GET / HTTP/1.1" 500 -