I don't completely understand your question but will the little I can deduce from it, first your func1 returns 0, make it return x and then define another method, the + method which will look like +(a::ConcType, b::ConcType) = ConcType(a.attr+b.attr)
now calling func2(foo) should return ConcType(51626) refer to the modint.jl in the julia example folder
