human
Solve the following python programming problem given the following code:
@pytest.mark.parametrize('arg', ['', 'arg'])
def test_setup_teardown_function_level_with_optional_argument(testdir, monkeypatch, arg):
assistant
#Here is the Python code you requested.

    """parameter to setup/teardown xunit-style functions parameter is now optional (#1728).
    """
    import sys
    trace_setups_teardowns = []
    monkeypatch.setattr(sys, 'trace_setups_teardowns', trace_setups_teardowns, raising=False)
    p = testdir.makepyfile("\n                                import    pytest\n                                import    sys\n\n                                trace    =    sys.trace_setups_teardowns.append\n\n                                def    setup_module({arg}):    trace('setup_module')\n                                def    teardown_module({arg}):    trace('teardown_module')\n\n                                def    setup_function({arg}):    trace('setup_function')\n                                def    teardown_function({arg}):    trace('teardown_function')\n\n                                def    test_function_1():    pass\n                                def    test_function_2():    pass\n\n                                class    Test(object):\n                                                def    setup_method(self,    {arg}):    trace('setup_method')\n                                                def    teardown_method(self,    {arg}):    trace('teardown_method')\n\n                                                def    test_method_1(self):    pass\n                                                def    test_method_2(self):    pass\n                ".format(arg=arg))
    result = testdir.inline_run(p)
    result.assertoutcome(passed=4)
    expected = ['setup_module', 'setup_function', 'teardown_function', 'setup_function', 'teardown_function', 'setup_method', 'teardown_method', 'setup_method', 'teardown_method', 'teardown_module']
    assert (trace_setups_teardowns == expected)