pub unsafe extern "C" fn dbus_connection_set_watch_functions(
    conn: *mut DBusConnection,
    add_function: DBusAddWatchFunction,
    remove_function: DBusRemoveWatchFunction,
    toggled_function: DBusWatchToggledFunction,
    data: *mut c_void,
    free_data_function: DBusFreeFunction
) -> u32