public Quantity GetQuantity(float value, string unit, string system, Coding code)
 {
     Quantity quantity = new Quantity();
     quantity.value = value;
     quantity.unit = unit;
     quantity.system = system;
     quantity.code = code;
     return quantity;
 }
 public Range GetRange(Quantity low, Quantity high)
 {
     Range range = new Range();
     range.low = low;
     range.high = high;
     return range;
 }
 public Ratio GetRatio(Quantity numerator, Quantity denominator)
 {
     Ratio ratio = new Ratio();
     ratio.numerator = numerator;
     ratio.denominator = denominator;
     return ratio;
 }