class Rufus::Scheduler::CronLine

def parse_item(item, min, max)
  return nil if item == '*'
  r = item.split(',').map { |i| parse_range(i.strip, min, max) }.flatten
  raise ArgumentError.new(
    "found duplicates in #{item.inspect}"
  ) if r.uniq.size < r.size
  r = sc_sort(r)
  Set.new(r)
end