flask-socketio(1) on Linux
The text 300a384e39ff, as Debian 11 (Bullseye) 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 official clients libraries in Javascript, C++, Java and Swift, or any compatible client to establish a permanent connection to the server.