Warning: TickDuration will be deprecated in the near future (once all uses of it in Phobos have been deprecated). Please use MonoTime for the cases where a monotonic timestamp is needed and Duration when a duration is needed, rather than using TickDuration. It has been decided that TickDuration is too confusing (e.g. it conflates a monotonic timestamp and a duration in monotonic clock ticks) and that having multiple duration types is too awkward and confusing.