1. I think this is too complex for the stdlib. One tool should do one thing. What about the PEP for this project? 2. This is very particular. For those who often convert data in different ways, but do not use pandas, attrs, SQL... 3. What about `typing`? 4. OTF code generation (if I understood correctly) is an debugging hell. 5. `pylint` has "several complaints" about the code.