>>> def comunicate():
...     print("passo1")
...     i = 0
...     try:
...         while True:
...             yield i
...             i += 1
...     except StopIteration:
...         print "passo3"
...
>>>
>>> a = comunicate()
>>> a.next()
passo1
0
>>> a.next()
1
>>> a.next()
2
>>> a.throw(StopIteration)
passo3
Traceback (most recent call last):
  File "<console>", line 1, in <module>
StopIteration
>>>