docstr: Get graph object
  Parameters
  ----------
  idx : int
      Item index
  Returns
  -------
  :class:`dgl.DGLGraph`
docstr_tok: ["Get","graph","object","Parameters","--","--","--","--","--","idx",":","int","Item","index","Returns","--","--","--","-",":","class",":","`","dgl.DGLGraph","`"]
code: def __getitem__(self, idx):
      r"""Get graph object
      Parameters
      ----------
      idx : int
          Item index
      Returns
      -------
      :class:`dgl.DGLGraph`
      """
      assert idx == 0, "This dataset has only one graph"
      return self.graph
  
file_path: dgl/examples/pytorch/gas/dataloader.py
imports: import os
  import dgl
  import numpy
  import scipy.io
  import torch
  from dgl.data import DGLBuiltinDataset
  from dgl.data.utils import _get_dgl_url, load_graphs, save_graphs
label_desc: Use image node_id 8 for calling the GASDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: self