code: def test_popscore_quantile(rng):
      algo = basic.PopScore()
      algo.fit(lktu.ml_test.ratings)
  
      assert algo.item_scores_.max() == 1.0
  
      counts = lktu.ml_test.ratings.groupby("item").user.count()
      counts = counts.sort_values()
  
      winner = counts.index[-1]
      assert algo.item_scores_.loc[winner] == 1.0
  
file_path: lkpy/tests/test_popular.py
imports: from lenskit.algorithms import basic
  import pandas
  import numpy
  import pickle
  import lenskit.util.test
label_desc: Use image node_id 5 for calling a global function with example usage: test_popscore_quantile(rng) without return types