code: def __getitem__(self, item):
      outputs = []
      for d in self.datasets:
          output = d[item]
          if len(output) < 2:
              outputs.append(output[0])
          else:
              outputs.append(output)
      return outputs
  
imports: from unittest import TestCase
  import operator
  import pytest
  import torch
  from torch.utils.data import TensorDataset, DataLoader, Dataset
  from torch import nn
  import torchmetrics
  from bigdl.nano.pytorch import Trainer
  from bigdl.nano.utils.common import compare_version
label_desc: Use image node_id 2 for calling the ChainTensorDataset obj's underlying member method code with example usage: obj.__getitem__(item) and returns: outputs