CODE:

example_dict = {"level1_key1": "1",
                        "level1_key2": {
                            "level2_key1": "2",
                            "level2_key2": {
                                "level3_key1": "Max depth"
                            }
                        }
                        }

        flatten_dict = {}

        def process_dict(dict_val):
            for key, val in dict_val.items():
                print(key, val)
                if isinstance(val, dict) and val:
                    process_dict(val)
                else:
                    flatten_dict.update({key: val})
            return flatten_dict


        print(process_dict(example_dict))

----------------------------------------

RESULT:

level1_key1 1
level1_key2 {'level2_key1': '2', 'level2_key2': {'level3_key1': 'Max depth'}}
level2_key1 2
level2_key2 {'level3_key1': 'Max depth'}
level3_key1 Max depth
{'level1_key1': '1', 'level2_key1': '2', 'level3_key1': 'Max depth'}