private static SimpleRange discontinuityBetween(Range1D belowRange, Range1D aboveRange)
{
int gap = aboveRange.start - belowRange.extent();
if (gap > 0)
{
return(new SimpleRange(belowRange.extent(), gap));
}
// throw new Exception("good to know if this happens. discon between got a null range. no gap?");
return(SimpleRange.theErsatzNullRange());
}