Which portions of the repertory of Ordinary time Sundays are left unused in the given range of liturgical years?

skipped_ordinary_time_sundays2.rb

# Which portions of the repertory of Ordinary time Sundays
# (lessons, corresponding chants of the Mass and Divine Office)
# are left unused in the given range of liturgical years?

require 'calendarium-romanum/cr'
require 'set'

SUNDAYS = (2..33).to_a.freeze
SANCTORALE = CR::Data::GENERAL_ROMAN_ENGLISH.load

all = Set.new
SUNDAYS.each do |i|
  %w(A B C).each do |c|
    all << "#{i}#{c}"
  end
end

years =
  if ARGV.empty?
    2020 .. 2030
  else
    ARGV[0].to_i .. ARGV[1].to_i
  end

years.each do |year|
  cal = CR::Calendar.new year, SANCTORALE

  date = cal.temporale.start_date
  loop do
    date += 7
    break if date > cal.temporale.end_date
    day = cal[date]

    if day.season == CR::Seasons::ORDINARY && day.celebrations[0].rank.sunday?
      all.delete "#{day.season_week}#{cal.lectionary}"
    end
  end
end

puts all.to_a.sort