/**
  * Get an instance of this class.
  *
  * @return GFCoupons
  */
 public static function get_instance()
 {
     if (self::$_instance == null) {
         self::$_instance = new GFCoupons();
     }
     return self::$_instance;
 }
function gf_coupons()
{
    return GFCoupons::get_instance();
}