class Singleton { private static $_instance = null; private function __construct() { // Some initialization code here } public static function getInstance() { if (!self::$_instance) { self::$_instance = new Singleton(); } return self::$_instance; } }In the above example, the Singleton class has a private constructor, meaning that it can only be instantiated from within the class itself. The getInstance method checks if the class has already been instantiated, and if not, creates a new instance of the class. This design pattern can be used in a variety of situations, such as creating a database connection or initializing a configuration object. It ensures that these resources are only created once, preventing issues related to duplicated objects. The package library for this design pattern is likely the singleton pattern library.