def METHOD_NAME():
    y = [None, 1, 2, None, None, 5, None, 7, None]
    filled = _fill_missing_data(y, max_gap_fraction=0.5)
    assert filled == [None, 1, 2, 3, 4, 5, 6, 7, None]
    filled = _fill_missing_data(y, max_gap_fraction=0.1)
    assert filled == [None, 1, 2, None, None, 5, 6, 7, None]