code: def add_inverse_distances(self, indices, periodic=True, indices2=None):
          
          from .distances import InverseDistanceFeature
          atom_pairs = _parse_pairwise_input(
              indices, indices2, self.logger, fname='add_inverse_distances()')
  
          atom_pairs = self._check_indices(atom_pairs)
          f = InverseDistanceFeature(self.topology, atom_pairs, periodic=periodic)
          self.__add_feature(f)
docs: Adds the inverse distances between atoms to the feature list.
  
          Parameters
          ----------
          indices : can be of two types:
  
                  ndarray((n, 2), dtype=int):
                      n x 2 array with the pairs of atoms between which the inverse distances shall be computed
  
                  iterable of integers (either list or ndarray(n, dtype=int)):
                      indices (not pairs of indices) of the atoms between which the inverse distances shall be computed.
  
          periodic : optional, boolean, default is True
              If periodic is True and the trajectory contains unitcell information,
              distances will be computed under the minimum image convention.
  
          indices2: iterable of integers (either list or ndarray(n, dtype=int)), optional:
                      Only has effect if :py:obj:`indices` is an iterable of integers. Instead of the above behaviour,
                      only the inverse distances between the atoms in :py:obj:`indices` and :py:obj:`indices2` will be computed.
  
  
          .. note::
              When using the *iterable of integers* input, :py:obj:`indices` and :py:obj:`indices2`
              will be sorted numerically and made unique before converting them to a pairlist.
              Please look carefully at the output of :py:func:`describe()` to see what features exactly have been added.