def test_strip_Nones():
    x = [None, None]
    assert Policy.strip_Nones(x) == []
    x = [1, 2, None]
    assert Policy.strip_Nones(x) == [1, 2]
    x = [[1, 2, 3], [4, None, None]]
    assert Policy.strip_Nones(x) == [[1, 2, 3], [4, -1, -1]]