e state as before.
    </p>
    <p>
        Note that <code>onCommand</code> and <code>onEvent</code> are both called during normal
        actor message dispatch so they can safely access and modify an actor's mutable state,
        however as persisting is done asynchronously they are not invoked through a single message.
        Nonetheless eventuate guarantees by default that no new command slips between an
        <code>onCommand</code>-call and the <code>onEvent</code>-calls for each emitted/persisted