> undecidable to say what a function does (happy to see some practical examples if someone has some) Any and all functions that involve templating/plugins/meta

> undecidable to say what a function does (happy to see some practical examples if someone has some) Any and all functions that involve templating/plugins/metaprogramming/etc (common in various web frameworks) that can effectively run arbitrary code and thus are undecidable. Also any function that does deserialization and thus will instantiate novel objects with their code, e.g. Python code that uses pickle will often be undecidable as its execution will depend on what exactly is unpickled.