static LongRange dateStructureToTimestampRange(DateStructures.SomeDate d) {
  ret dateStructureToTimestampRange(d, localTimeZone(), now(), true);
}

static LongRange dateStructureToTimestampRange(DateStructures.SomeDate d, TimeZone tz, long now, bool assumeFuture) {
  delegate Day to DateStructures.
  delegate Month to DateStructures.
  delegate Year to DateStructures.
  delegate CurrentWeekPlus to DateStructures.
  delegate CurrentYearPlus to DateStructures.
  delegate Weekday to DateStructures.
  delegate TodayPlus to DateStructures.
  
  // year
  
  if (d instanceof CurrentYearPlus)
    d = new Year(year(now) + ((CurrentYearPlus) d).nYears);
  if (d cast Year)
    ret longRange(yearToTimestamp(d.year, tz), yearToTimestamp(d.year+1, tz));
    
  // month
  
  if (d instanceof CurrentMonthPlus)
    d = new Month(month(now) + ((CurrentMonthPlus) d).nMonths, ((CurrentMonthPlus) d).year);
  if (d instanceof Month)
    ret longRange(yearAndMonthToTimestamp(((Year) d.year).year, d.month);

  fail("dateStructureToTimestampRange: unknown type" + d);
}