def unimonth!
      all_months_txt_rxs = MONTHS.map { |m| instance_variable_get("@#{m}".to_sym) }.join('|')
      @month_txt = Regexp.new("(?<month>#{all_months_txt_rxs})", true)
    end
def unimonth!
      all_months_txt_rxs = MONTHS.map { |m| instance_variable_get("@#{m}".to_sym) }.join('|')
      @month_txt = Regexp.new("(?<month>#{all_months_txt_rxs})", true)
    end
Sets @month_txt, a compound of all month regexps that matches any month name