Struct RealTimeDuration
sealed struct RealTimeDuration
Represents a span of time calculated from a comparison between
two RealTimeInstant’s. This type follows ISO 8601 Duration definition.
This type is functionally equivalent to MonotonicDuration but
it puts an emphasis on incompatibility between monotonic and real-time
time measurements.
Just like MonotonicInstant cannot be compared to RealTimeInstant,
RealTimeDuration cannot be added to a MonotonicInstant.
