class_docstr: 自定义数据集
code: def collate_fn(batch):
      # 官方实现的default_collate可以参考
      # https://github.com/pytorch/pytorch/blob/67b7e751e6b5931a9f45274653f4f653a4e6cdf6/torch/utils/data/_utils/collate.py
      images, labels = tuple(zip(*batch))
  
      images = torch.stack(images, dim=0)
      labels = torch.as_tensor(labels)
      return images, labels
  
file_path: deep-learning-for-image-processing/pytorch_classification/train_multi_GPU/my_dataset.py
imports: from PIL import Image
  import torch
  from torch.utils.data import Dataset
label_desc: Use image node_id 4 for calling the MyDataSet obj's underlying member method code with example usage: obj.collate_fn(batch) and returns: images,  labels