The examples in v1_api_demo are using v1_api now, and will be upgraded into v2_api later.Thus, v1_api_demo is a temporary directory. We decide not to maintain it and will delete it in future.Please go to [PaddlePaddle/book](https://github.com/PaddlePaddle/book) and [PaddlePaddle/models](https://github.com/PaddlePaddle/models) to learn PaddlePaddle.