I twitched a little when I saw lists and dicts included as default arguments in one of the examples: def main( ..., obj: dict = {"even": "dicts"},

I twitched a little when I saw lists and dicts included as default arguments in one of the examples: def main( ..., obj: dict = {"even": "dicts"}, my_list: list = ["or", "lists!"], ... has modern python made these less footgun-y? the issue being that the code looks like 'obj' and 'my_list' are as provided in the default arguments every time the function is called, but the defaults are instantiated once and they can be modified inside the function: def foo(msgs=["hello"]): print(msgs) msgs.append("world") foo() # prints ['hello'] foo() # prints ['hello', 'world'] foo() # prints ['hello', 'world', 'world'] Nonetheless, introspecting on default arguments like that looks like a fine way to turn functions into UI elements if you're going to contrive that those functions aren't going to be re-entered multiple times in the same python runtime.