I mean doctest: https://docs.python.org/3/library/doctest.html
2. Serialize as/to doctests. Is there a good way to serialize Python objects as Python code?
3. Add doctests to callables' docstrings with AST
Mutation testing tools may have already implemented serialization to doctests but IDK about docstring modification.
... MOSES is an evolutionary algorithm that mutates and simplifies a combo tree until it has built a function with less error for the given input/output pairs.