def METHOD_NAME() -> None:
    m = Metadatable(metadata={"6": 7})
    assert m.snapshot_base() == {}
    assert m.snapshot() == {"metadata": {"6": 7}}
    del m.metadata["6"]
    assert m.snapshot() == {}
    sb = HasSnapshotBase(metadata={"7": 8})
    assert sb.snapshot_base() == {"cheese": "gruyere"}
    assert sb.snapshot() == {"cheese": "gruyere", "metadata": {"7": 8}}
    del sb.metadata["7"]
    assert sb.snapshot() == sb.snapshot_base()
    s = HasSnapshot(metadata={"8": 9})
    assert s.snapshot() == {'fruit': 'kiwi'}
    assert s.snapshot_base() == {}
    assert s.metadata == {"8": 9}