code: def test_rsl_callable_metric():
      # metric is the function reference, not the string key.
      metric = distance.euclidean
  
      labels, tree = robust_single_linkage(X, 0.4, metric=metric)
      n_clusters_1 = len(set(labels)) - int(-1 in labels)
      assert n_clusters_1 == n_clusters
  
      labels = RobustSingleLinkage(metric=metric).fit(X).labels_
      n_clusters_2 = len(set(labels)) - int(-1 in labels)
      assert n_clusters_2 == n_clusters
  
imports: import numpy
  from scipy.spatial import distance
  from scipy import sparse
  from sklearn.utils.estimator_checks import check_estimator
  from sklearn.utils._testing import assert_array_equal, assert_raises
  from hdbscan import RobustSingleLinkage, robust_single_linkage
  from sklearn import datasets
  import warnings
  from sklearn.datasets import make_blobs
  from sklearn.utils import shuffle
  from sklearn.preprocessing import StandardScaler
  import pytest
label_desc: Use image node_id 3 for calling a global function with example usage: test_rsl_callable_metric() without return types