You could just write this as (a is None) is not (b is None) or (a is None) != (b is None) It won't make a difference (and is 1 to to 5 characters lo

You could just write this as (a is None) is not (b is None) or (a is None) != (b is None) It won't make a difference (and is 1 to to 5 characters longer), but it seems "cleaner" since it's more specific.