reference counting example

>>>
>>> class ListaQueAvisaQuandoMorre(list):
...     def __del__(self):
...         print(f"Lista com id {id(self)} destruida")
...
...
>>> a = ListaQueAvisaQuandoMorre([10, 20, 30])
>>> del a
Lista com id 140337716637024 destruida
>>> a = ListaQueAvisaQuandoMorre([10, 20, 30])
>>> gerad = (v for v in a)
>>> del a
>>> print(next(gerad))
10
>>> print(next(gerad))
20
>>> print(next(gerad))
30
>>> print(next(gerad))
Lista com id 140337716637024 destruida
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration
>>> del gerad
>>>