'Sort a comment according to the Q&A-type sort.
Arguments:
* children -- a list of the children of this comment.
* responder_ids -- a set of ids of users categorized as "answerers" for
this thread.'

def _qa(self, children, responder_ids):

    op_children = [c for c in children if (c.author_id in responder_ids)]
    score = sorts.qa(self._ups, self._downs, len(self.body), op_children)
    if ((self.author_id in responder_ids) and (not op_children)):
        score *= 2
    return score
