def ocurrences(st, en = nil)
      recurrence ?
        recurrence.events(:starts => st, :until => en) :
        (start_at.to_date..end_at.to_date).to_a
    end
def ocurrences(st, en = nil)
      recurrence ?
        recurrence.events(:starts => st, :until => en) :
        (start_at.to_date..end_at.to_date).to_a
    end
Array including all the dates this Scheduler has ocurrences
 between st and en