It's worth pointing out that python expands the datatype of numbers as needed (ending up at BigInt or similar, I belive). So any stack rewriting would have to a

It's worth pointing out that python expands the datatype of numbers as needed (ending up at BigInt or similar, I belive). So any stack rewriting would have to accommodate an accumulator that starts as an integer and expands to arbitrarily many bits. It might be easily handled as I guess all arguments are references to python objects, and the regular code for expanding numbers could switch out the reference - but the point remains that proper tail call optimization in python needs to deal with objects as arguments.