To connect to a WebSocket server, create a [class@Session] and call [method@Session.websocket_connect_async]. To accept WebSocket connections,
create a [class@Server] and add a handler to it with [method@Server.add_websocket_handler].
(Lower-level support is available via [func@websocket_client_prepare_handshake] and [func@websocket_client_verify_handshake], for handling the
client side of the WebSocket handshake, and [func@websocket_server_process_handshake] for handling the server side.)
WebsocketConnection handles the details of WebSocket communication. You can use [
method@WebsocketConnection.send_text] and [method@WebsocketConnection.send_binary] to send data, and the [signal@WebsocketConnection:
SoupWebsocketConnection:message] signal to receive data. (WebsocketConnection currently only supports
asynchronous I/O.)