To set mass fractions
function X input Types.Concentration tNa = 135, tHCO3 = 24, tK = 5, tGlucose = 5, tUrea = 1.5, tCl = 105, tCa = 1.5, tMg = 0.5, tAlb = 0.7; input Types.MassConcentration tGlb = 28, tOthers = 1e-6; output Types.MassFraction X[nS]; end X;