code: def length(self) -> int:
      split_lengths = {
          _Split.TRAIN: 1_281_167,
          _Split.VAL: 50_000,
          _Split.TEST: 100_000,
      }
      return split_lengths[self]
  
imports: import csv
  from enum import Enum
  import logging
  import os
  from typing import Callable, List, Optional, Tuple, Union
  import numpy
  from .extended import ExtendedVisionDataset
label_desc: Use image node_id 1 for calling the _Split obj's underlying member method code with example usage: obj.length() and returns: split_lengths