code: def __getitem__(self, index):
      ann = self.annotation[index]
  
      image = Image.open(ann["image"]).convert("RGB")
      image = self.transform(image)
      caption = pre_caption(ann["caption"], 30)
  
      return image, caption
  
file_path: blip/data/pretrain_dataset.py
imports: import json
  import os
  import random
  from torch.utils.data import Dataset
  from PIL import Image
  from PIL import ImageFile
  from data.utils import pre_caption
  import os, glob
label_desc: Use image node_id 4 for calling the pretrain_dataset obj's underlying member method code with example usage: obj.__getitem__(index) and returns: image,  caption