How to implement “__iadd__()” for an immutable type?

Question

I would like to subclass an immutable type or implement one of my own which behaves like an int does as shown in the following console session:

Answer 1

class aug_int:
    def __init__(self, value):
        self.value = value

    def __iadd__(self, other):
        self.value += other
        return self

>>> i = aug_int(34)
>>> i
<__main__.aug_int instance at 0x02368E68>
>>> i.value
34
>>> i += 55
>>> i
<__main__.aug_int instance at 0x02368E68>
>>> i.value
89
>>>