code: def __getitem__(self, idx):
      assert idx == 0, "This dataset has only one graph"
      return self.graph[idx], self.labels
  
file_path: ogb/ogb/nodeproppred/dataset_dgl.py
imports: import pandas
  import shutil, os
  import os.path
  import torch
  import numpy
  from dgl.data.utils import load_graphs, save_graphs, Subset
  import dgl
  from ogb.utils.url import decide_download, download_url, extract_zip
  from ogb.io.read_graph_dgl import read_graph_dgl, read_heterograph_dgl
  from ogb.io.read_graph_raw import read_node_label_hetero, read_nodesplitidx_split_hetero
label_desc: Use image node_id 4 for calling the DglNodePropPredDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self,  self