flask-socketio(1) on Linux
The text 9bbb65c00c15, as Debian 12 (Bookworm) shipped it.
flask-socketio Documentation Flask-SocketIO gives Flask applications access to low latency bi-directional communications between the clients and the server. The client-side application can use any of the SocketIO client libraries in Javascript, Python, C++, Java and Swift, or any other compatible client to establish a permanent connection to the server.