docstr: Length of the dataset
  Returns
  -------
  int
      Length of Dataset
docstr_tok: ["Length","of","the","dataset","Returns","--","--","--","-","int","Length","of","Dataset"]
code: def __len__(self):
      """Length of the dataset
      Returns
      -------
      int
          Length of Dataset
      """
      return len(self.smiles_list)
  
file_path: dgl/examples/pytorch/ogb_lsc/PCQM4M/test_inference.py
imports: import argparse
  import os
  import random
  import dgl
  import numpy
  import torch
  from gnn import GNN
  from ogb.lsc import PCQM4MDataset, PCQM4MEvaluator
  from ogb.utils import smiles2graph
  from torch.utils.data import DataLoader
  from tqdm import tqdm
label_desc: Use image node_id 3 for calling the OnTheFlyPCQMDataset obj's underlying member method code with example usage: obj.__len__() and returns: len