Which sanctorale feasts are celebrated on inverse dates like 2/5 x 5/2?

inverse_date_feasts.rb

# Which sanctorale feasts are celebrated on inverse dates like 2/5 x 5/2?

require 'calendarium-romanum/cr'

class CR::AbstractDate
  def inverse
    return nil if day > 12 || day == month
    self.class.new(day, month)
  end
end

def format(date, celebrations)
  "#{date.month}/#{date.day} " +
    celebrations.collect(&:symbol).join(', ')
end

cal = ARGV[0] || 'universal-en'

sanctorale = CR::Data[cal].load_with_parents
sanctorale.each_day do |date, celebrations|
  inverse = date.inverse
  next unless inverse && !sanctorale[inverse].empty?
  next if inverse < date # print each pair only once

  print format date, celebrations
  print ' x '
  puts format inverse, sanctorale[inverse]
end