pub fn get_device_info<Conn, A>(
    conn: &Conn,
    device_spec: DeviceSpec,
    wanted: XIFeature,
    all_buttons: bool,
    first_button: u8,
    n_buttons: u8,
    led_class: LedClass,
    led_id: A
) -> Result<Cookie<'_, Conn, GetDeviceInfoReply>, ConnectionError>
where Conn: RequestConnection + ?Sized, A: Into<IDSpec>,