public static function usps($package, $country, $shipping_to)
 {
     $api_url = 'http://production.shippingapis.com/ShippingAPI.dll';
     $shipping_from = get_field('shipping_from', 'option');
     if ($package['total_cost'] == 0 || $package['total_weight'] == 0) {
         return array();
     }
     //perform validation here
     //Create package
     $package = UFStoreShippingUSPS::usps_create_package($package, $country, $shipping_to, $shipping_from);
     //Execute CURL
     $response = UFStoreShippingUSPS::execute_curl($api_url . $package);
     //Sort through it
     $shipping_options = UFStoreShippingUSPS::parse_response_xml($response, $country);
     return $shipping_options;
 }