[supercheetah]

I think that's the point is that it does seem rather ambiguous as to the intent. If someone is new to programming entirely, what are they thinking is happening with an operation *on obj.a or obj.b? If they know other languages and are just starting out learning Python, what expectations are they bringing from those languages?

If I had had magic wand, I'd make operations on class attributes from an instance a syntax error, and only allow it from the class name, and perhaps with special syntax like in C++, e.g.:

    A::a = (1,)
    A::b = [1,]

*edit: operation on obj.a or obj.b...