Function tokio_tungstenite::client_async_tls

pub fn client_async_tls<R, S>(
    request: R, 
    stream: S
) -> Box<Future<Item = (WebSocketStream<StreamSwitcher<S, TlsStream<S>>>, Response), Error = Error>> where
    R: Into<Request<'static>>,
    S: 'static + AsyncRead + AsyncWrite + NoDelay, 

Creates a WebSocket handshake from a request and a stream, upgrading the stream to TLS if required.