How to use the websocket API?

I read the docks but it doesn't explain how communication work between client and server.

And [this example command](https://alphacephei.com/vosk/server#testing-with-microphone) does not work. It says `-u` flag doesn't exist.
```
./test_microphone.py -u ws://localhost:2700
```

My main goal is to trigger voice recognition from the microphone using a shortcut key and get the `text` vosk recognized and write it.