I think it's even more safe/preferable to use non-mutable `None`s as a default and do:
``` def myfunc(x=None): x = x if x is not None else [] ... ```
``` def myfunc(x=None): x = x if x is not None else [] ... ```
x = x or []
Your method is best when you might get falsy values but if that’s not an issue the `or` method is handy.