fluent python read record

>>> a = (1, 2, [1,2,3])
>>> a[2] += [4,5]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> a
(1, 2, [1, 2, 3, 4, 5])
>>>