def add_contacts(self, indices, indices2=None, threshold=0.3, periodic=True, count_contacts=False):
        r
        from .distances import ContactFeature
        atom_pairs = _parse_pairwise_input(
            indices, indices2, self.logger, fname='add_contacts()')
        atom_pairs = self._check_indices(atom_pairs)
        f = ContactFeature(self.topology, atom_pairs, threshold, periodic, count_contacts)
        self.__add_feature(f)