code: def get_feature_index(
      feature: Union[int, slice]
  ) -> Union[int, slice]:
      """
      Returns a modified feature index: in case of a slice of size 1, returns the corresponding integer. In case
      of a slice with missing params, tries to fill them. Otherwise, returns the same value (integer or slice) as passed.
  
      :param feature: The index or slice representing a feature to attack
      :return: An integer representing a single column index or a slice representing a multi-column index
      """
      if isinstance(feature, int):
          return feature
  
      start = feature.start
      stop = feature.stop
      step = feature.step
      if start is None:
          start = 0
      if step is None:
          step = 1
      if stop is not None and ((stop - start) // step) == 1:
          return start
  
      return slice(start, stop, step)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import logging
  import math
  import os
  import shutil
  import sys
  import tarfile
  import warnings
  import zipfile
  from functools import wraps
  from inspect import signature
  from typing import TYPE_CHECKING, Callable, List, Dict, Optional, Tuple, Union
  import numpy
  import six
  from scipy.special import gammainc
  from tqdm.auto import tqdm
  from art import config
label_desc: Use image node_id 20 for calling a global function with example usage: get_feature_index(feature) and returns: slice, feature, start