docs: def make_index_lookup(list_, dict_factory=dict):
      r"""
      Args:
          list_ (list): assumed to have unique items
  
      Returns:
          dict: mapping from item to index
  
      CommandLine:
          python -m utool.util_list --exec-make_index_lookup
  
      Example:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_list import *  # NOQA
          >>> import utool as ut
          >>> list_ = [5, 3, 8, 2]
          >>> idx2_item = ut.make_index_lookup(list_)
          >>> result = ut.repr2(idx2_item, nl=False)
          >>> assert ut.dict_take(idx2_item, list_) == list(range(len(list_)))
          >>> print(result)
          {2: 3, 3: 1, 5: 0, 8: 2}
      """
      return dict_factory(zip(list_, range(len(list_))))