def interpret_datemonthly_variant
      hash_for_occ_base = { type: :datemonthly, interval: interval }
      array_of_occurrences = []
      repeats_on.each do |date_of_month|
        h = { date_of_month: date_of_month }
        array_of_occurrences << hash_for_occ_base.merge(h)
      end
      array_of_occurrences
    end
def interpret_datemonthly_variant
      hash_for_occ_base = { type: :datemonthly, interval: interval }
      array_of_occurrences = []
      repeats_on.each do |date_of_month|
        h = { date_of_month: date_of_month }
        array_of_occurrences << hash_for_occ_base.merge(h)
      end
      array_of_occurrences
    end
repeats_on is an array of datemonthly indices.  For example,
 "the 21st and 22nd of every monthy" will produce repeats_on == [21, 22]