def METHOD_NAME(
    vstate: FullSumState,
    Ô: DiscreteOperator,
    use_covariance: TrueT,
    *,
    mutable: CollectionFilter,
) -> tuple[Stats, PyTree]:
    Ō, Ō_grad = expect_and_forces(vstate, Ô, mutable=mutable)
    Ō_grad = _force_to_grad(Ō_grad, vstate.parameters)
    return Ō, Ō_grad