/**
  * INSTANCE
  *
  * Ensures only one instance of Sticky_Post_Expiration is loaded or can be loaded.
  *
  * @since 1.0.0
  * @static
  * @see Sticky_Post_Expiration()
  * @return Sticky_Post_Expiration - Main instance
  */
 public static function instance($version, $plugin_path, $plugin_url, $plugin_file)
 {
     if (is_null(self::$instance)) {
         self::$instance = new self($version, $plugin_path, $plugin_url, $plugin_file);
     }
     return self::$instance;
 }
<?php

/* Plugin Name:  Sticky Post Expiration
 * Plugin URI:   http://ebenhale.com/sticky-post-expiration
 * Version:      1.0.0
 * Description:  This WordPress plugin allows the user to set a sticky post expiration date
 * Author:       Eben Hale
 * Author URI:   http://ebenhale.com/
 * License:      GPL-2.0+
 * License URI:  http://www.gnu.org/licenses/gpl-2.0.txt
 *
 */
/*
 * Exit if called directly.
 */
if (!defined('WPINC')) {
    die;
}
require_once 'includes/class-sticky-post-expiration.php';
Sticky_Post_Expiration::instance('1.0.0', plugin_dir_path(__FILE__), plugin_dir_url(__FILE__), plugin_basename(__DIR__) . '.php');