-record(cron_plan, {
    minute :: automata@cron@normalize:int_set(),
    hour :: automata@cron@normalize:int_set(),
    day_of_month :: automata@cron@normalize:int_set(),
    month :: automata@cron@normalize:int_set(),
    day_of_week :: automata@cron@normalize:int_set()
}).