[Python] Access to protected class attributes from object methods

I'm learning OOP in python and ran into a problem. How to correctly access protected class attributes from object methods? Example code:

from typing import ClassVar


class Example:
_foo: ClassVar[int] = 2
def bar(self) -> int:
return self._foo

def baz(self, num: int) -> None:
self._foo = num

if __name__ == "__main__":
example1 = Example()
example2 = Example()
example1.baz(1)
print(example1.bar())


But mypy says:

error: Cannot assign to class variable "_foo" via instance [misc]


Ok, let's try this: self.__class__._foo. And misses again! Now ruff is swearing:

SLF001 Private member accessed: `_foo`
|
9 | def baz(self, num: int) -> None:
10 | self.__class__._foo = num
| ^^^^^^^^^^^^^^^^^^^ SLF001
11 |
12 | if __name__ == "__main__":
|


So what's the right way?

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