def __init__( self, volume_path: Union[str, Path], minimum_file_number: int = 64, extensions: Tuple = ( ".cb", ".png", ".tif", ".tiff", ".jpg", ".jpeg", ), volume_info_file_name: str = VOLUME_INFO_FILE_NAME, ) -> None: self.volume_path = Path(volume_path).resolve() self.minimum_file_number = minimum_file_number self.extensions = extensions self.volume_info_path = Path(self.volume_path, volume_info_file_name) self.__image_files: List[Path] = None assert self.volume_path.is_dir()请完整详细解释每一行代码的意思

这段代码是一个Python类的构造函数，用于初始化类的属性。以下是每一行代码的意思：

- def __init__(self, volume_path: Union[str, Path], minimum_file_number: int = 64, extensions: Tuple = (".cb", ".png", ".tif", ".tiff", ".jpg", ".jpeg", ), volume_info_file_name: str = VOLUME_INFO_FILE_NAME, ) -> None:
这是构造函数的头部，其中包括参数列表和返回值。它接收一个必要参数volume_path和三个可选参数minimum_file_number、extensions、volume_info_file_name，返回None。

- self.volume_path = Path(volume_path).resolve()
这一行代码将传入的volume_path参数转换为Path对象，并使用.resolve()方法获取绝对路径，并将其赋值给类的volume_path属性。

- self.minimum_file_number = minimum_file_number
这一行代码将minimum_file_number参数的值直接赋给类的minimum_file_number属性。

- self.extensions = extensions
这一行代码将extensions参数的值直接赋给类的extensions属性。

- self.volume_info_path = Path(self.volume_path, volume_info_file_name)
这一行代码使用已解析的volume_path和volume_info_file_name参数创建一个新的Path对象，并将其赋值给类的volume_info_path属性。

- self.__image_files: List[Path] = None
这一行代码定义了一个私有属性__image_files，使用Python类型提示说明其类型为List[Path]，初始值为None。

- assert self.volume_path.is_dir()
这一行代码使用断言检查volume_path是否为一个目录，如果不是，则会抛出AssertionError。