'Send responses and make sure errors are handled.
:param dict chall_update: parameter that is updated to hold
authzr -> list of outstanding solved annotated challenges'

def _send_responses(self, achalls, resps, chall_update):

    active_achalls = []
    for (achall, resp) in six.moves.zip(achalls, resps):
        active_achalls.append(achall)
        if ((resp is not None) and resp):
            self.acme.answer_challenge(achall.challb, resp)
            if (achall.domain in chall_update):
                chall_update[achall.domain].append(achall)
            else:
                chall_update[achall.domain] = [achall]
    return active_achalls
