class_docstr: Subset of a dataset at specified indices.
  Arguments:
      dataset (Dataset): The whole Dataset
      indices (sequence): Indices in the whole set selected for subset
code: def __init__(self, dataset, indices, mode="train"):
      self.dataset = dataset
      if paddle.distributed.get_world_size() == 1 or mode != "train":
          self.indices = indices
      else:
          self.indices = indices[
              int(paddle.distributed.get_rank()) :: int(
                  paddle.distributed.get_world_size()
              )
          ]
  
      self.mode = mode
  
imports: import os
  import sys
  import json
  import numpy
  import glob
  import copy
  import time
  import argparse
  from collections import OrderedDict, namedtuple
  from scipy.sparse import csr_matrix
  from ogb.graphproppred import GraphPropPredDataset
  from ogb.utils.features import get_atom_feature_dims, get_bond_feature_dims
  import pgl
  import paddle
  from pgl.utils.data.dataset import Dataset, StreamDataset, HadoopDataset
  from pgl.utils.data import Dataloader
  from pgl.utils.logger import log
  from utils.config import prepare_config, make_dir
label_desc: Use image node_id 1 to create a new Subset object from inherited base classes: Dataset with example: obj = Subset(dataset, indices, mode)