public Period(Time start, Interval length)
{
this.start = start;
this.length = length;
}
public Period(Time start, Time end)
{
this.start = start;
this.length = end.Interval(start);
}
public static Time Add(this Time time, Interval interval)
{
return new Time (time.SecondsFromEpoch + interval.Seconds, time.Context);
}