class Rufus::Scheduler

def occurrences(time0, time1, format=:per_job)
  h = {}
  jobs.each do |j|
    os = j.occurrences(time0, time1)
    h[j] = os if os.any?
  end
  if format == :timeline
    a = []
    h.each { |j, ts| ts.each { |t| a << [ t, j ] } }
    a.sort_by { |(t, j)| t }
  else
    h
  end
end