code: def __len__(self):
      return len(self.data)
  
imports: import json
  import os
  from collections import Counter
  import torch
  import torchvision
  import torchvision.transforms
  from PIL import Image
  from torch import nn
  from torch.utils.data import Dataset
label_desc: Use image node_id 2 for calling the JsonlDataset obj's underlying member method code with example usage: obj.__len__() and returns: len