How to :GetMass() of a model?

function GetMassOfModel(model)
	local mass = 0
	for i, v in pairs(model:GetChildren()) do
		if v:IsA('BasePart') or v:IsA('Union') then
			mass = mass + v:GetMass()
		end
	end
	return mass
end

Something like that; When this function is called on a model (as the argument), it iterates through each object in the model specified, checks if it's a physical object, and then adds that object's mass into a total (the mass variable), returning the variable when it's done iterating.