static function Instance()
 {
     if (null === MainWP_Child_Back_Up_Wordpress::$instance) {
         MainWP_Child_Back_Up_Wordpress::$instance = new MainWP_Child_Back_Up_Wordpress();
     }
     return MainWP_Child_Back_Up_Wordpress::$instance;
 }
 function backup_wp()
 {
     if (!version_compare(phpversion(), '5.3', '>=')) {
         $error = sprintf(__('PHP Version %s is unsupported.', 'mainwp-child'), phpversion());
         MainWP_Helper::write(array('error' => $error));
     }
     MainWP_Child_Back_Up_Wordpress::Instance()->action();
 }