Subclass `pathlib.Path` fails

I would like to enhance the class pathlib.Path but the simple example above dose not work.

from pathlib import Path

class PPath(Path):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

test = PPath("dir", "test.txt")

Here is the error message I have.

Traceback (most recent call last):
  File "/Users/projetmbc/test.py", line 14, in <module>
    test = PPath("dir", "test.txt")
  File "/anaconda/lib/python3.4/pathlib.py", line 907, in __new__
    self = cls._from_parts(args, init=False)
  File "/anaconda/lib/python3.4/pathlib.py", line 589, in _from_parts
    drv, root, parts = self._parse_args(args)
  File "/anaconda/lib/python3.4/pathlib.py", line 582, in _parse_args
    return cls._flavour.parse_parts(parts)
AttributeError: type object 'PPath' has no attribute '_flavour'

What I am doing wrong ?

With the latest Python version, _flavour, _posix_flavour are deprecated and we can pass flavour keyword in our class.

import os
from pathlib import Path


class PPath(Path):
    def __init__(self, *args) -> None:
        # Determine the flavor based on the operating system
        flavour = 'posix' if os.name == 'posix' else 'windows'

        # Pass the flavor to the superclass constructor
        super().__init__(*args, flavour=flavour)