message: Start adding more tests...
  ... but there is a bug
diff: @@ -199,6 +199,14 @@ def test_cubical_generators_from_vertices():
  assert np.array_equal(g[0][1], np.array([[14, 10]]))
  assert np.array_equal(g[1][0], np.array([14]))
  + cub = CubicalComplex(vertices=[[2, 1, 6, 8],
  + [5, 9, 4, 7],
  + [4, 7, 3, 9]])
  + assert set(cub.persistence()) == {(1, (7.0, 9.0)), (0, (1.0, inf)), (0, (3.0, 6.0)), (0, (4.0, 5.0))}
  + g = cub.vertices_of_persistence_pairs()
  + assert g[1] == [[3]]
  + assert len(g[0]) == 2 and np.array_equal(g[0][0], [[2, 1], [8, 6]]) and np.array_equal(g[0][1], [[5, 4]])
  +
  def test_periodic_cubical_generators_from_vertices():
  cub = PeriodicCubicalComplex(vertices = [[0, 0, 0, 0], [0, 1, 1, 0], [0, 1, 1, 0], [0, 0, 0, 0]], periodic_dimensions=[False, False])
  cub.persistence()
  @@ -209,6 +217,11 @@ def test_periodic_cubical_generators_from_vertices():
  assert np.array_equal(g[0][1], np.array([[15, 10]]))
  assert np.array_equal(g[1][0], np.array([0]))
  + cub = PeriodicCubicalComplex(vertices=[[2, 1, 6, 8],
  + [5, 9, 4, 0],
  + [4, 7, 3, 9]], periodic_dimensions=(True, True))
  + #TODO
  +
  def test_cubical_cofaces_of_persistence_pairs_when_pd_has_no_paired_birth_and_death():
  cubCpx = CubicalComplex(dimensions=[1,2], top_dimensional_cells=[0.0, 1.0])
  Diag = cubCpx.persistence(homology_coeff_field=2, min_persistence=0)
  