(I'm very new to this coroutine part so It's not supposed to attack these modules, just I don't know the differences)
atfer version 2.5, python officially support coroutine with yield. and then, why greenlet, gevent, Stackless python are still useful? it there somthing that "yield" can't do or just it is easier or powerful? -- http://mail.python.org/mailman/listinfo/python-list
