Flask app.run(ssl_context='adhoc') has no effect

I am trying to have a basic Flask app run on "https":

from flask import Flaskapp = Flask(__name__)@app.route('/')def hello_world():    return 'Hello World!'if __name__ == '__main__':    app.run(ssl_context='adhoc')

However, it starts on http:

• Running on http://127.0.0.1:5000

In fact, I have a more elaborate Flask app that I moved onto https a couple of days ago, and it worked! However, I started it again today, and it got stuck on http://.

So, I created the basic script shown above to see if it works, but it doesn't.

I'll be grateful for any hints..

Thanks!