docs: def get_random(self):
          """Get a kitten, either from the db, or a new one.
          """
          num_kittens = self.count()
          new_cutoff = (num_kittens / (num_kittens + constants.KITTEN_FRESHNESS))
          if random.random() < new_cutoff:
              return self._rand_inst()
          else:
              return self.create_new()