class Rufus::Scheduler::CronLine

def frequency
  delta = 366 * DAY_S
  t0 = previous_time(Time.local(2000, 1, 1))
  loop do
    break if delta <= 1
    break if delta <= 60 && @seconds && @seconds.size == 1
    t1 = next_time(t0)
    d = t1 - t0
    delta = d if d < delta
    break if @months == nil && t1.month == 2
    break if t1.year == 2001
    t0 = t1
  end
  delta
end