docs: public static String dateSub(long ts, int days, TimeZone tz) {
  		ZoneId zoneId = tz.toZoneId();
  		Instant instant = Instant.ofEpochMilli(ts);
  		ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, zoneId);
  		long resultTs = zdt.minusDays(days).toInstant().toEpochMilli();
  		return dateFormat(resultTs, DATE_FORMAT_STRING, tz);
  	}