code: def __init__(self):
      super(PEMS_BAYTrainDataset, self).__init__(
          "data", "pems_bay_train.npz"
      )
      self.mean = self.x[..., 0].mean()
      self.std = self.x[..., 0].std()
  
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 1 to create a new PEMS_BAYTrainDataset object from inherited base classes: SnapShotDataset with example: obj = PEMS_BAYTrainDataset()