code: def __len__(self):
      return len(self.x)
  
imports: import os
  import ssl
  import dgl
  import numpy
  import torch
  from six.moves import urllib
  from torch.utils.data import DataLoader, Dataset
label_desc: Use image node_id 2 for calling the SnapShotDataset obj's underlying member method code with example usage: obj.__len__() and returns: len