This gist is used in the tutorial https://www.vijayan.in/how-to-create-custom-table-list-in-wordpress-admin-page

constant_and_property.php

<?php
...
 
	/**
	 * Const to declare number of posts to show per page in the table.
	 */
	const POSTS_PER_PAGE = 10;

	/**
	 * Property to store post types
	 *
	 * @var  array Array of post types
	 */
	private $allowed_post_types;
...