code: def test_unrated_selector():
      sel = basic.UnratedItemCandidateSelector()
      s2 = sel.fit(simple_df)
      assert s2 is sel
  
      assert set(sel.candidates(10)) == set([3])
      assert set(sel.candidates(12)) == set([3, 2])
      assert set(sel.candidates(11)) == set([1, 2, 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 3 for calling a global function with example usage: test_unrated_selector() without return types