How to use the dtaidistance.alignment.best_alignment function in dtaidistance

def test_sequences2():
    s1 = "GAAAAAAAT"
    s2 = "GAAT"
    value, matrix = alignment.needleman_wunsch(s1, s2)
    algn, s1a1, s2a1 = alignment.best_alignment(matrix, s1, s2, gap='-')
    algn_sol1 = [list('GAAAAAAAT'), list('GAA-----T')]
    assert s1a1 == algn_sol1[0]
    assert s2a1 == algn_sol1[1]

def test_sequences4():
    s1 = "AGACTAGTTACC"
    s2 = "CGAGACGTC"
    value, matrix = alignment.needleman_wunsch(s1, s2)
    algn, s1a1, s2a1 = alignment.best_alignment(matrix, s1, s2, gap='-')
    # print(matrix)
    # print(algn)
    # print(s1a1)
    # print(s2a1)
    algn_sol1 = [list("--AGACTAGTTACC"), list("CGAGAC--GT--C-")]
    assert s1a1 == algn_sol1[0]
    assert s2a1 == algn_sol1[1]

def test_sequences3():
    s1 = "GAAAAAAAT"
    s2 = "GAATA"
    value, matrix = alignment.needleman_wunsch(s1, s2)
    algn, s1a1, s2a1 = alignment.best_alignment(matrix, s1, s2, gap='-')
    algn_sol1 = [list('GAA-AAAAAT'), list('GAATA-----')]
    assert s1a1 == algn_sol1[0]
    assert s2a1 == algn_sol1[1]

def test_sequences1():
    """Example from https://en.wikipedia.org/wiki/Needleman–Wunsch_algorithm . """
    s1 = "GATTACA"
    s2 = "GCATGCU"
    value, matrix = alignment.needleman_wunsch(s1, s2)
    algn, s1a1, s2a1 = alignment.best_alignment(matrix, s1, s2, gap='-')
    matrix_sol = [
        [-0., -1., -2., -3., -4., -5., -6., -7.],
        [-1.,  1., -0., -1., -2., -3., -4., -5.],
        [-2., -0., -0.,  1., -0., -1., -2., -3.],
        [-3., -1., -1., -0.,  2.,  1., -0., -1.],
        [-4., -2., -2., -1.,  1.,  1., -0., -1.],
        [-5., -3., -3., -1., -0., -0., -0., -1.],
        [-6., -4., -2., -2., -1., -1.,  1., -0.],
        [-7., -5., -3., -1., -2., -2., -0., -0.]]
    algn_sol1 = [['G', '-', 'A', 'T', 'T', 'A', 'C', 'A'], ['G', 'C', 'A', 'T', '-', 'G', 'C', 'U']]
    assert value == 0.0
    assert np.array_equal(matrix, matrix_sol)
    assert s1a1 == algn_sol1[0]
    assert s2a1 == algn_sol1[1]