code: def __len__(self):
      return len(self.annotation)
  
file_path: blip/data/nocaps_dataset.py
imports: import os
  import json
  from torch.utils.data import Dataset
  from torchvision.datasets.utils import download_url
  from PIL import Image
label_desc: Use image node_id 2 for calling the nocaps_eval obj's underlying member method code with example usage: obj.__len__() and returns: len