private static Units CombineUnits(Units a, Units b, Func <int, int, int> combine)
{
List <UnitExponent> data = new List <UnitExponent>();
foreach (SIUnitType u in Enum.GetValues(typeof(SIUnitType)))
{
int exp = combine(a.ExponentFor(u), b.ExponentFor(u));
if (exp != 0)
{
data.Add(new UnitExponent(u, exp));
}
}
return(new Units(data));
}