Operator "+=" overloading for class?

[Ki Rill]

On Sunday, 17 December 2023 at 04:13:20 UTC, Ki Rill wrote:
> I am trying to overload `opOpAssign` for my class. The code 
> [...]
> 

I forgot to mention, it is relevant to 
[`Value`](https://github.com/rillki/tiny-grad/blob/main/source/rk/tgrad/core/value.d) class only.