code: def create_native_pay_url(self, productid):
          
  
          params, sign, = self._pay_sign_dict(productid=productid)
  
          params['sign'] = sign
  
          return NATIVE_BASE_URL + urlencode(params)
docs: 创建 native pay url
          详情请参考 支付开发文档
  
          :param productid: 本地商品ID
          :return: 返回URL