Shortcode to list all lessons within a course in Woo Sensei

woo-sensei-list-lessons-shortcode.php

<?php
  
  	/**
	 * List lessons by course
	 *
	 * Generates the shortcode that outputs the list of the lessons for a given course.
	 *
	 * @return string The HTML Layout output of the Course Lessons.
	 */
	function lessons_shortcode_func(){
		$args = [
			'post_type' => 'lesson',
			'posts_per_page' => 99,
			'orderby' => 'meta_value_num',
			'meta_key' => '_order_51',
			'order'=> 'ASC',
			'meta_query' => [
				'key' => '_lesson_course',
				'value' => '51'
			]
		];

		$lessons = get_posts( $args );
		$output = null;
		foreach($lessons as $lesson){
			$output .= $lesson->post_title . '<br>';
		}
		return $output;
	}
	add_shortcode( 'list-lessons', 'lessons_shortcode_func' );
	

Thanks for this