code: def get_rating(postid, userid):
          '''
          Get the rating of certain post and user.
          '''
          try:
              recs = TabRating.select().where(
                  (TabRating.post_id == postid) & (TabRating.user_id == userid)
              )
          except:
              return False
          if recs.count() > 0:
              return recs.get().rating
          else:
              return Falsf get_rating(postid, userid):
          '''
          Get the rating of certain post and user.
          '''
          try:
              recs = TabRating.select().where(
                  (TabRating.post_id == postid) & (TabRating.user_id == userid)
              )
          except:
              return False
          if recs.count() > 0:
              return recs.get().rating
          else:
              return False
docs: Get the rating of certain post and user.