digraph{
    graph [
        bgcolor="#FFFFFFF00",
        rankdir=LR,
        ];
    free_keys [
      label="Wait for free-keys\nfrom the scheduler",
      shape=box,style=dashed,
    ];
    memory -> free_keys;
    error -> free_keys;
    free_keys -> released;
    rescheduled -> released;
    released -> forgotten;
}
