/**
  * Provide default gateway settings fields.
  *
  * @param 	array $settings
  * @param 	Charitable_Gateway $gateway 	The gateway's helper object.
  * @return  array
  * @access  public
  * @since   1.0.0
  */
 public function register_gateway_settings($settings, Charitable_Gateway $gateway)
 {
     add_filter('charitable_settings_fields_gateways_gateway_' . $gateway->get_gateway_id(), array($gateway, 'default_gateway_settings'), 5);
     add_filter('charitable_settings_fields_gateways_gateway_' . $gateway->get_gateway_id(), array($gateway, 'gateway_settings'), 15);
     return apply_filters('charitable_settings_fields_gateways_gateway_' . $gateway->get_gateway_id(), $settings);
 }