How to use the birdseye.utils.flatten_list function in birdseye

def test_is_lambda(self):
        self.assertTrue(is_lambda(lambda: 0))
        self.assertTrue(is_lambda(lambda x, y: x + y))
        self.assertFalse(is_lambda(min))
        self.assertFalse(is_lambda(flatten_list))
        self.assertFalse(is_lambda(self.test_is_lambda))

def check(inp, out):
            self.assertEqual(flatten_list(inp), out)

code_info = self._code_infos.get(new_func.__code__)
        if code_info:
            return new_func

        lines, start_lineno = inspect.getsourcelines(func)  # type: List[Text], int
        end_lineno = start_lineno + len(lines)
        name = safe_qualname(func)
        source_file = inspect.getsourcefile(func)
        if source_file.startswith('

code_info = self._code_infos.get(new_func.__code__)
        if code_info:
            return new_func

        lines, start_lineno = inspect.getsourcelines(func)  # type: List[Text], int
        end_lineno = start_lineno + len(lines)
        name = safe_qualname(func)
        source_file = inspect.getsourcefile(func)
        if source_file.startswith('