code: def test_empty():
      sel = basic.EmptyCandidateSelector()
  
      res = sel.candidates(42)
      assert res.tolist() == []
  
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 1 for calling a global function with example usage: test_empty() without return types