# What happened to sage.coding.relative_finite_field_extension?

I have been using this "experimental" module since 2019, and as recently as two months ago (February 2023) sans any problems or changes to my code over that period. As of today, using Sage 9.8, importing the module throws a ModuleNotFound Error (below). This happens using Sage kernel 9.6, 9.7, 9.8. Using kernel 9.5, all is fine (the library is loaded OK). I have a hard time thinking the code is "gone" from Sage, but cannot find any documentation about changes to it (moved to a different module?). This is a "yoohoo! functionality gone from Sage!" surprise that surely other users like me must be stumped by. Pleading for help! Thanks.

```
ModuleNotFoundError Traceback (most recent call last)
/tmp/ipykernel_1412/1244373623.py in <module>
----> 1 from sage.coding.relative_finite_field_extension import *
2 F64 = GF(Integer(64), names=('W',)); (W,) = F64._first_ngens(1)
3
4 # Finite field of order 2^96 generated by WW over F2.
5 F2k = GF(Integer(64)**Integer(16), names=('WW',)); (WW,) = F2k._first_ngens(1)
ModuleNotFoundError: No module named 'sage.coding.relative_finite_field_extension'
'SageMath version 9.8, Release Date: 2023-02-11'
```

This experimental code has been removed (https://github.com/sagemath/sage/issu...) but other standard methods have been added (https://github.com/sagemath/sage/issu...). Hope it helps.

Thanks. The vector_space method realizes the isomorphism of field extensions providing exactly the functionality in relative_finite_field_extension that I was using.