code: def _notify_delete(self, index_or_slice):
          
          if isinstance(index_or_slice, int):
              length = len(self)
              if -length <= index_or_slice < length:
                  self._notify_remove_at(index_or_slice)
                  return lambda: self._notify_add_at(index_or_slice)
          elif isinstance(index_or_slice, slice):
              slice_ = slice(*index_or_slice.indices(len(self)))
              self._notify_remove(slice_)
              return lambda: self._notify_add(index_or_slice)
docs: Notify about a deletion at an index_or_slice.
  
          :return: a function that notifies about an add at the same place.