async def METHOD_NAME(c: "Client", s: "Scheduler", a: "Worker", b: "Worker") -> None:
    await DaskStorage(name="foo")
    ext = s.extensions["optuna"]
    assert len(ext.storages) == 1
    assert type(ext.storages["foo"]) is optuna.storages.InMemoryStorage
    await DaskStorage(name="bar")
    assert len(ext.storages) == 2
    assert type(ext.storages["bar"]) is optuna.storages.InMemoryStorage