read_chunks on Path 2

import os
import pathlib


class Path(pathlib.Path):
    def __new__(cls, *args, **kwargs):
        if cls is Path:
            cls = WindowsPath if os.name == 'nt' else PosixPath
        self = cls._from_parts(args, init=False)
        if not self._flavour.is_supported:
            raise NotImplementedError("cannot instantiate %r on your system"
                                      % (cls.__name__,))
        self._init()
        return self
    def read_chunks(self, size=1024, *, mode='rb'):
        with self.open(mode) as f:
            sentinel = b'' if 'b' in mode else ''
            for chunk in iter(lambda: f.read(size), sentinel):
                yield chunk


class PosixPath(Path, pathlib.PurePosixPath):
    __slots__ = ()


class WindowsPath(Path, pathlib.PureWindowsPath):
    __slots__ = ()