New generator feature: Generate useful glue for output arrays, so you can just write values to the output array (no bounds checking). Rewrote UNPACK_SEQUENCE_TWO_TUPLE to use this, and also UNPACK_SEQUENCE_{TUPLE,LIST}.
You can now write things like this:
```
inst(BUILD_STRING, (pieces[oparg] -- str)) { ... }
inst(LIST_APPEND, (list, unused[oparg-1], v -- list, unused[oparg-1])) { ... }
```
Note that array output effects are only partially supported (they must be named `unused` or correspond to an input effect).
- This doesn't cover everything (far from it) but it's a start.
- This uses pytest, which isn't ideal, but was quickest to get started.
Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
Guido van Rossum
Irit Katriel