code: def _sk_reference(preds, target, fn):
      """Compute reference values using sklearn."""
      return fn(target, preds)
  
file_path: torchmetrics/tests/unittests/clustering/test_homogeneity_completeness_v_measure.py
imports: from functools import partial
  import pytest
  from sklearn.metrics import completeness_score
  from sklearn.metrics import homogeneity_score
  from sklearn.metrics import v_measure_score
  from torchmetrics.clustering.homogeneity_completeness_v_measure import CompletenessScore, HomogeneityScore, VMeasureScore
  from torchmetrics.functional.clustering.homogeneity_completeness_v_measure import completeness_score, homogeneity_score, v_measure_score
  from unittests.clustering.inputs import _float_inputs_extrinsic, _single_target_extrinsic1, _single_target_extrinsic2
  from unittests.helpers import seed_all
  from unittests.helpers.testers import MetricTester
label_desc: Use image node_id 1 for calling a global function with example usage: _sk_reference(preds, target, fn) and returns: fn