code: def __len__(self):
      return len(self.annotation)
  
imports: import os
  import math
  from lavis.datasets.datasets.base_dataset import BaseDataset
  from lavis.datasets.datasets.caption_datasets import CaptionDataset
label_desc: Use image node_id 2 for calling the VideoCaptionEvalDataset obj's underlying member method code with example usage: obj.__len__() and returns: len