code: def test_user_based_field(u1_ml100k, pkf):
      """Ensure that the user_based field is taken into account (only) when
      needed."""
  
      algorithms = (KNNBasic, KNNWithMeans, KNNBaseline)
      for klass in algorithms:
          algo = klass(sim_options={"user_based": True})
          rmses_user_based = cross_validate(
              algo, u1_ml100k, ["rmse"], pkf
          )["test_rmse"]
          algo = klass(sim_options={"user_based": False})
          rmses_item_based = cross_validate(
              algo, u1_ml100k, ["rmse"], pkf
          )["test_rmse"]
          assert rmses_user_based != rmses_item_based
  
imports: from itertools import combinations
  import pytest
  from surprise import KNNBaseline, KNNBasic, KNNWithMeans
  from surprise.model_selection import cross_validate
label_desc: Use image node_id 2 for calling a global function with example usage: test_user_based_field(u1_ml100k, pkf) without return types