https://stackoverflow.com/questions/48024720/python-how-to-check-if-socket-is-still-connected

Random other links:
- https://www.geeksforgeeks.org/socket-programming-multi-threading-python/
- https://discuss.python.org/t/making-a-multi-thread-server-for-a-chat-room-destination-client-sockets-selection/8572/8
- https://docs.python.org/3/library/socketserver.html