How to use the aiofiles.base.AiofilesContextManager function in aiofiles

def open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None,
         closefd=True, opener=None, *, loop=None, executor=None):
    return AiofilesContextManager(_open(file, mode=mode, buffering=buffering,
                                        encoding=encoding, errors=errors,
                                        newline=newline, closefd=closefd,
                                        opener=opener, loop=loop,
                                        executor=executor))

def __init__(
        self, file_path: Union[str, PathLike], *, buffer_size: Optional[int] = None
    ) -> None:
        self.file_path = file_path_to_path(file_path)
        self.size = self.file_path.stat().st_size
        self.begin = 0
        self.end = self.size
        if buffer_size is not None:
            self.buffer_size = buffer_size
        self.file: Optional[AsyncFileIO] = None
        self.file_manager: Optional[AiofilesContextManager] = None