Are tuples immutable?

[perfringo]

This can be also worth of knowing about tuples immutability:

>>> spam = (1, [2, 3])
>>> spam[1] += [4, 5]            # will throw error but still mutate list within tuple
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> spam
(1, [2, 3, 4, 5])