def test_not_constant():
assert not _is_constant([0, 0, 0, 0, [8]])
assert not _is_constant([0, 0, [8], 0, 0])
assert not _is_constant([[7], [6], 0, 0, 0])
assert not _is_constant([0, 0, [9], [10], 0])
assert not _is_constant([[1], [2], [8], 0, 0])
assert not _is_constant([[1], [2], [8], [3], 0])
def test_all_absent():
assert _is_constant([0, 0, 0, 0])
def test_all_present():
assert _is_constant([[2], [1], [4], [5], [3]])