get course users total numbers shortcode

<?php 

/**
 * Shortcode get course total users number
 * 
 * @since 2.1.0
 * 
 * @param  array    $atts   shortcode attributes
 * @return string   course total users number
 */
function wn_course_access_list($atts) {
    $atts = shortcode_atts( array(
        'course_id' => 0,
    ), $atts, 'course_access_list' );

    if( empty($atts["course_id"]) || $atts["course_id"] == 0 || FALSE === get_post_status( $atts["course_id"] )) {
        return;
    }

    $course_users_query     = learndash_get_users_for_course( $atts["course_id"], array(), false );
    $user_ids               = $course_users_query->get_results();
    $total_users            = count($user_ids);

    return $total_users;
}
add_shortcode( "course_access_list", "wn_course_access_list" );