code: def test_unrated_override():
      sel = basic.UnratedItemCandidateSelector()
      sel.fit(simple_df)
  
      assert set(sel.candidates(10, [2])) == set([1, 3])
  
file_path: lkpy/tests/test_candidate_selector.py
imports: from lenskit.algorithms import basic
  import lenskit.util.test
  import pandas
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: test_unrated_override() without return types