Writing python code, according to everything I can find this should work and is how you do callable functions as arguments, but it is saying "_get_simple_test_result() missing 1 required positional argument: 'test'" def _get_simple_test_result(self, test: Test): return {"name": test.name, "suite": self.data.suites[test.parent].name, "status": test.status} def _aggregate_results_list(self, process_test: Callable[[Test], any] = _get_simple_test_result) -> list: results: list = [] for test in self.data.tests.values(): if self._test_matches_filter(test): results.append(process_test(test)) return results Any input would be greatly appreciated. The argument is being passed to the process test function, not sure why it is saying it is missing. Continue reading...