'Returns tuple of (\'completed\', \'failed\').'

def _handle_check(self, domain, achalls):

    completed = []
    failed = []
    (self.authzr[domain], _) = self.acme.poll(self.authzr[domain])
    if (self.authzr[domain].body.status == messages.STATUS_VALID):
        return (achalls, [])
    for achall in achalls:
        updated_achall = achall.update(challb=self._find_updated_challb(self.authzr[domain], achall))
        if (updated_achall.status == messages.STATUS_VALID):
            completed.append((achall, updated_achall))
        elif (updated_achall.status == messages.STATUS_INVALID):
            failed.append((achall, updated_achall))
    return (completed, failed)
