def test_recurring(value):
    assert DateFormat(value) == value
def test_approx_date(value):
    assert DateFormat(value) == value
def test_open_date_range(value):
    assert DateFormat(value) == value
def test_closed_date_range(value):
    assert DateFormat(value) == value
def test_parse_duration(value):
    assert DateFormat(value) == value
def test_parse_simple_date(value):
    assert DateFormat(value) == value
def test_if_bad_format_raises_exceptions(value):
    with pytest.raises(ValueError):
        DateFormat(value)