<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def update_count(self):
 """ updates comment count """

        node_rating_count = self.node.rating_count
        node_rating_count.comment_count = self.node.comment_set.count()
        node_rating_count.save()