>>> gen = ((yield)+(yield) for _ in range(2))
>>> gen.next()
>>> gen.send(100)
>>> gen.send(200)
300
>>> gen.next()
>>> gen.send(500)
>>> gen.send(120)
620
>>> gen.next()

Traceback (most recent call last):
  File "<pyshell#113>", line 1, in <module>
    gen.next()
StopIteration
>>>