Edit File: SingletonTrait.php
<?php /** * Singleton class trait. * * @package Kkart\Utilities */ namespace Automattic\Kkart\RestApi\Utilities; /** * Singleton trait. */ trait SingletonTrait { /** * The single instance of the class. * * @var object */ protected static $instance = null; /** * Constructor * * @return void */ protected function __construct() {} /** * Get class instance. * * @return object Instance. */ final public static function instance() { if ( null === static::$instance ) { static::$instance = new static(); } return static::$instance; } /** * Prevent cloning. */ private function __clone() {} /** * Prevent unserializing. */ final public function __wakeup() { kkart_doing_it_wrong( __FUNCTION__, __( 'Unserializing instances of this class is forbidden.', 'kkart' ), '4.6' ); die(); } }