So what does (inout int = 0) do?

[w0rp via Digitalmars-d]

I think it has something to do with making the function, in this 
case a lambda, inout, so that it can accept inout types. Then the 
typeof bit is a weird way to writing something like 
__traits(compiles, ...) , because functions which have no type 
result in void, and that fails the typeof check.

If we do end up replacing inout with something else, I would like 
something which solves the problem of declaring functions 
returning ranges of either mutable, const, or immutable. I've 
struggled with that before: 
https://github.com/w0rp/dstruct/blob/master/source/dstruct/graph.d#L628