Using opOpAssign, cannot assign sequence

[Alex]

class X(T)
	void opOpAssign(string op)(T d)

If T has more than length of one then

x += ????

We can work around this but it seems to me that we should be able 
to get it to work in some way

x += Alias!(a,b,c)

fails to package it up as do all other things I have tried.

void Add(Ts d) { opOpAssign!("+")(d); }

Then x.Add(a,b,c) works fine.

But of course defeats the entire purpose of opOpAssigns short 
hand notation.