public function testGetSub()
 {
     $postage = new Product(Config::get());
     $response = $postage->getSub();
     $this->assertTrue(is_array($response));
     foreach ($response as $value) {
         $this->assertArrayHasKey('id', $value);
         $this->assertArrayHasKey('name', $value);
     }
     $postage = new Product(Config::get());
     $response = $postage->getSub(537891948);
     $this->assertTrue(is_array($response));
     foreach ($response as $value) {
         $this->assertArrayHasKey('id', $value);
         $this->assertArrayHasKey('name', $value);
     }
     return $response[2]['id'];
 }