There are two issues with that: - what is the dummy value? does the value type even have one? - I don't think index-assignment (or attribute-assignment) is ov

There are two issues with that: - what is the dummy value? does the value type even have one? - I don't think index-assignment (or attribute-assignment) is overloadable in C++, so you need `a[b]` to return something which can be assigned to, and proxy values tend to be really wonky (see: `vector<bool>`), so assigning to the result of the indexing would replace the dummy value