I also thought that, but `math.factorial` is a builtin, and so you cannot get the signature of it, and the code can't determine how many operands the command ne

I also thought that, but `math.factorial` is a builtin, and so you cannot get the signature of it, and the code can't determine how many operands the command needs. This is similar to the `self.stack.clear()` example. (`signature(math.factorial)` gives "ValueError: no signature found for builtin <built-in function factorial>")