def test_or() -> None:
    'Test ``Or`` condition. '

    @argcomb(Or('a', 'b'))
    def f(a: Any=None, b: Any=None) -> None:
        ...
    f(a=1)
    f(b=2)
    f(a=1, b=2)
    with pytest.raises(InvalidArgumentCombination):
        f()
Test ``Or`` condition.
def test_or() -> None:
    ' '

    @argcomb(Or('a', 'b'))
    def f(a: Any=None, b: Any=None) -> None:
        ...
    f(a=1)
    f(b=2)
    f(a=1, b=2)
    with pytest.raises(InvalidArgumentCombination):
        f()