A Python Riddle

From the book Fluent Python (which you can get from the Humble Bundle right now):

What would the following piece of code do?

t = (1, 2, [30, 40])
t[2] += [50, 60]

Four choices:

1. t becomes (1,2,[30,40,50,60])
2. A TypeError is raised because tuples does not support item assignments?
3. Neither
4. Both 1. and 2.

The answer is the link, which is quite surprising.

It turns out that t[2].extend([50, 60])doesn’t break Python, and this riddle is really a super esoteric corner case…