code: def test_bias_index_props():
      algo = Bias()
      algo.fit(simple_df)
      assert all(
          np.sort(algo.user_index) == np.unique(simple_df["user"])
      )
      assert all(
          np.sort(algo.item_index) == np.unique(simple_df["item"])
      )
  
imports: from lenskit.algorithms.bias import Bias
  from lenskit import util
  import logging
  import pickle
  import binpickle
  import pandas
  import numpy
  from pytest import approx, raises, mark
  from lenskit.util.test import ml_test
label_desc: Use image node_id 7 for calling a global function with example usage: test_bias_index_props() without return types