项目场景：

MNIST数据集 GANs生成

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问题描述：

完整报错：

Traceback (most recent call last):
  File "pytorch_MNIST_cGAN.py", line 229, in <module>
    for x_, y_ in train_loader:
  File "/root/anaconda3/envs/dpm-pc-gen/lib/python3.7/site-packages/torch/utils/data/dataloader.py", line 521, in __next__
    data = self._next_data()
  File "/root/anaconda3/envs/dpm-pc-gen/lib/python3.7/site-packages/torch/utils/data/dataloader.py", line 561, in _next_data
    data = self._dataset_fetcher.fetch(index)  # may raise StopIteration
  File "/root/anaconda3/envs/dpm-pc-gen/lib/python3.7/site-packages/torch/utils/data/_utils/fetch.py", line 44, in fetch
    data = [self.dataset[idx] for idx in possibly_batched_index]
  File "/root/anaconda3/envs/dpm-pc-gen/lib/python3.7/site-packages/torch/utils/data/_utils/fetch.py