static function _init()
 {
     //load abstract class
     st()->load_libs(array('abstract/class-abstract-payment-gateway'));
     //Load default gateways
     self::_load_default_gateways();
     self::$_payment_gateways = array('st_submit_form' => new STGatewaySubmitform(), 'st_paypal' => new STGatewayPaypal());
     add_action('init', array(__CLASS__, '_do_add_gateway_options'));
 }