class_docstr: Base class for MNIST, cifar10, etc.
code: def __getitem__(self, idx):
      if self._transform is not None:
          return self._transform(self._data[idx], self._label[idx])
      return self._data[idx], self._label[idx]
  
imports: import os
  from ...None import recordio, ndarray
  from ...util import default_array
label_desc: Use image node_id 2 for calling the _DownloadedDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self,  self, self