code: def _load_extra(self, extra_path: str) -> np.ndarray:
      extra_full_path = self._get_extra_full_path(extra_path)
      return np.load(extra_full_path, mmap_mode="r")
  
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 4 for calling the ImageNet obj's underlying member method code with example usage: obj._load_extra(extra_path) and returns: np