class_docstr: Subset of a dataset at specified indices.
docstr: getitem
docstr_tok: ["getitem"]
code: def __getitem__(self, idx):
      """getitem"""
      return self.dataset[self.indices[idx]]
  
imports: import os
  import sys
  import numpy
  from sklearn.model_selection import StratifiedKFold
  import paddle
  from pgl.utils.data import Dataset
  from pgl.utils.data import Dataloader
  import pgl
  from pgl.utils.logger import log
label_desc: Use image node_id 2 for calling the Subset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self