static double getValueInUnits(LengthUnits units, double?imperial, double?metric, bool round = false) => getValueInUnits(units.IsImperial(), imperial, metric, round);
static string getUnitString(this LengthUnits unit) => unit.IsImperial() ? "in" : "mm";
static double getValueInUnits (LengthUnits units, double? imperial, double? metric, bool round = false) => getValueInUnits (units.IsImperial (), imperial, metric, round);