apply_filters( 'can_add_user_to_blog', true|WP_Error $retval, int $user_id, string $role, int $blog_id )

176	 * @param true|WP_Error $retval  True if the user should be added to the site, error177	 *                               object otherwise.178	 * @param int           $user_id User ID.179	 * @param string        $role    User role.180	 * @param int           $blog_id Site ID.181	 */182	$can_add_user = apply_filters( 'can_add_user_to_blog', true, $user_id, $role, $blog_id );183 184	if ( true !== $can_add_user ) {185		restore_current_blog();186 187		if ( is_wp_error( $can_add_user ) ) {188			return $can_add_user;