Function dial_ws 

pub fn dial_ws(
    url: String,
    subprotocol: String,
    on_open: Value,
    on_message: Value,
    program: Arc<Program>,
    policy: Policy,
) -> Result<Value, String>

net.dial_ws(url, subprotocol, on_open, on_message) -> [net, E] Result[Unit, Str]. Blocks for the lifetime of the connection; returns Ok(()) on a clean close from the server, Err(reason) on dial failure, handshake failure, read error, or write error.