class_docstr: A `Pytorch Geometric <https://pytorch-geometric.readthedocs.io/en/latest/index.html>`_ data interface for datasets used in molecule generation.
  
  .. note::
      When creating data loaders of this dataset class, only dig.ggraph3D.dataset.collate_fn can be used as the collate function.
  
  Args:
      root (string, optional): Root directory where the dataset should be saved. (default: :obj:`./`)
      subset_idxs (list, optional): if it is not None, only the data located 
          at the indexs in subset_idxs of the dataset will be sampled.
          (default: :obj:`None`)
      transform (callable, optional): A function/transform that takes in an
          :obj:`torch_geometric.data.Data` object and returns a transformed
          version. The data object will be transformed before every access.
          (default: :obj:`None`)
      pre_transform (callable, optional): A function/transform that takes in
          an :obj:`torch_geometric.data.Data` object and returns a
          transformed version. The data object will be transformed before
          being saved to disk. (default: :obj:`None`)
      pre_filter (callable, optional): A function that takes in an
          :obj:`torch_geometric.data.Data` object and returns a boolean
          value, indicating whether the data object should be included in the
          final dataset. (default: :obj:`None`)
code: def raw_file_names(self):
      return "gdb9.sdf"
  
imports: import os
  import os.path
  import numpy
  import torch
  import networkx
  from networkx.algorithms import tree
  from math import pi
  from rdkit import Chem
  from rdkit.Chem.rdchem import BondType
  from torch_geometric.data import Data, InMemoryDataset, download_url, extract_tar
label_desc: Use image node_id 4 for calling the QM93DGEN obj's underlying member method code with example usage: obj.raw_file_names() and returns: str