from typing import Optional


class Image:
    __slots__ = ('path', 'hash', )

    path: Optional[str]
    hash: str

    def __init__(self, path: Optional[str], hash: str) -> None:
        self.path = path
        self.hash = hash

    def __repr__(self) -> str:
        return f'Image({repr(self.path)}, {repr(self.hash)})'


class ImageReference(Image):
    __slots__ = ('name', )

    name: str

    def __init__(self, name: str) -> None:
        # Intentionally do not call super()
        # This will cause AttributeError exceptions when someone
        # tries to access an image that's only a reference

        self.name = name

    def __repr__(self) -> str:
        return f'ImageReference({repr(self.name)})'