public IEnumerable <DateRange> SplitByHour()
{
if (Start.EndOfHour() == Stop.EndOfHour())
{
return new[] { this }
}
;
var t = Start.EndOfHour().AddTicks(1);
return(new[] { new DateRange(Start, t) }.Concat(new DateRange(t, Stop).SplitByHour()));
}