>>> class MyExc(Exception): pass
...
>>> import itertools
>>> async def gen():
...     for i in itertools.count():
...         try:
...             yield i
...         except MyExc:
...             pass
...
>>> agen = gen()
>>> agen.asend(None).send(None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration: 0
>>> athrow = agen.athrow(MyExc)
>>> athrow.throw(MyExc)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration: 1
>>> athrow.throw(MyExc)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration: 2
>>> athrow.throw(MyExc)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration: 3
>>> athrow.throw(MyExc)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration: 4
>>>