finality.py

from typing import final

@final
class Song:
    artist: str
    title: str
    album: str
    year: int

class Derived(Song):  # ERROR: Can't inherit from final class "Song"
    studio: str

# ---------------------

from typing import Final

class Song:
    artist: str
    title: str
    album: str
    year: Final = 2019
    

class 2020Song(Song):
    Final = 2020  # ERROR: Can't override a final field