def METHOD_NAME(self, ad_ag1, ad_ag2,
                              expected_pbc_dist):
    '''Ensure that pairwise distances between atoms are
    correctly calculated with PBCs.'''
    pairwise_pbc = (ad.AtomicDistances(ad_ag1, ad_ag2).run())
    actual = pairwise_pbc.results
    # compare with expected values from dist()
    assert_allclose(actual, expected_pbc_dist)