human
Solve the following python programming problem given the following code:
@pytest.mark.parametrize('value,    typ', [(None, None), (42, int)])
def test_conv_default_param(value, typ):
assistant
#Here is the Python code you requested.

    """The default value should always be a valid choice.
    """
    def func(foo=value):
        pass
    param = inspect.signature(func).parameters['foo']
    assert (argparser.type_conv(param, typ, value, str_choices=['val']) == value)