code: def test_split_keys_gcol():
      recs, truth = topn._df_keys(
          ["algorithm", "user", "item", "rank", "score", "fishtank"],
          ["user", "item", "rating"],
          ["algorithm", "fishtank", "user"],
      )
      assert truth == ["user"]
      assert recs == ["algorithm", "fishtank", "user"]
  
imports: from pathlib import Path
  import logging
  import numpy
  import pandas
  from pytest import approx, mark
  from lenskit.algorithms.user_knn import UserUser
  from lenskit.algorithms.item_knn import ItemItem
  from lenskit.algorithms.basic import PopScore
  from lenskit.algorithms.ranking import PlackettLuce
  from lenskit.algorithms import Recommender
  from lenskit.util.test import ml_test, demo_recs
  from lenskit.metrics.topn import _dcg, precision, recall
  from lenskit import topn, batch, crossfold
label_desc: Use image node_id 2 for calling a global function with example usage: test_split_keys_gcol() without return types