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

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