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/** (not working code)
 * Disable JetPack Nags
 *
 * @since 1.2.0
 */
function s9_disable_jetpack_nags() {
	remove_action( 'admin_notices', array( 'Jetpack_JITM', 'backups_updates_msg' ) );
	remove_action( 'admin_notices', array( 'Jetpack_JITM', 'akismet_msg' ) );
}
add_action( 'plugins_loaded', 's9_disable_jetpack_nags', 99 ); // This didn't work

// Per Jeremey's post, here: https://wordpress.org/support/topic/removing-wordpresscom-notices-when-page-editing/
add_filter( 'jetpack_just_in_time_msgs', '__return_false', 99 ); // This didn't work either