{TypeError}Object of type WebSocketService is not JSON serializable

[ddua123]

As mentioned in chats, I am trying to save the messages to a file.
def save_message(msg):
with open(f"{uuid.uuid4()}.json", 'w+') as fh:
fh.write(json.dumps(msg))

hub_connection = HubConnectionBuilder()
.with_url(SERVER_URL(design_id, connection_token), options={"verify_ssl": False,
"skip_negotiation": False,
"headers": {
"Cookie": "uac.authorization={}".format(token)
}
})
.configure_logging(logging.DEBUG, socket_trace=True, handler=handler)
.with_automatic_reconnect({
"type": "interval",
"keep_alive_interval": 10,
"intervals": [1, 3, 5, 6, 7, 87, 3]
}).build()

    hub_connection.on_open(lambda: print("connection opened and handshake received ready to send messages"))
    hub_connection.on_close(lambda: print("connection closed"))

    hub_connection.on("ReceiveMessage", self.save_message())

Please advice how to fix it, Also if I need to close the socket connection only after receiving a particular message(for eg close socket if I received word'completed' in it). How to do that.