text: const joda_tz = require('js-joda-timezone');
  const joda = require('js-joda').use(joda_tz);
  
  const { DateTimeFormatter } = joda;
  
  const hour_formatter = DateTimeFormatter.ofPattern('HH:mm');
  const hms_formatter = DateTimeFormatter.ofPattern('HH:mm:ss');
  const rfc3339_formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ssZ");
  
  module.exports = {
      hour_formatter,
      rfc3339_formatter,
  
      // convenience functions
      hour: date => hour_formatter.format(date),
      hms: date => hms_formatter.format(date),
      rfc3339: date => rfc3339_formatter.format(date)
  };
  