dataclass:
Person(name='John', age=40, musics=[Person.Music(name='Imagine')])
b'{"name":"John","age":40,"musics":[{"name":"Imagine"}]}'

TypedDict:
{'name': 'John', 'age': 40, 'musics': [{'name': 'Imagine'}]}
b'{"name":"John","age":40,"musics":[{"name":"Imagine"}]}'
