I used Fable 5.1 and Opus 5.5 to build a Python interpreter in Rust. Appears to pass all the 3.12 code I throw at it.
To get a toy version that can run most things takes under 2 hrs. Half of that time is collecting the tests you want to pass, how it should evaluate the code, what your criteria are, etc.
I wouldn't be surprised if "re-write Python" is in the training set.
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This is really what people conflagrate so often with these tasks, it is basically making the model do recall what could also be a "ant_ag_ds_90917_rwpy9_final" git clone
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And also the domain is very verifiable locally.