code: def test_identical_points():
      # Ensure identical points are handled correctly when using mst with
      # a sparse connectivity matrix
      X = np.array(
          [
              [0, 0, 0],
              [0, 0, 0],
              [1, 1, 1],
              [1, 1, 1],
              [2, 2, 2],
              [2, 2, 2],
          ]
      )
      true_labels = np.array([0, 0, 1, 1, 2, 2])
      connectivity = kneighbors_graph(
          X, n_neighbors=3, include_self=False
      )
      connectivity = 0.5 * (connectivity + connectivity.T)
      connectivity, n_components = _fix_connectivity(
          X, connectivity, "euclidean"
      )
  
      for linkage in ("single", "average", "average", "ward"):
          clustering = AgglomerativeClustering(
              n_clusters=3, linkage=linkage, connectivity=connectivity
          )
          clustering.fit(X)
  
          assert_almost_equal(
              normalized_mutual_info_score(
                  clustering.labels_, true_labels
              ),
              1,
          )
  
imports: import itertools
  import shutil
  from functools import partial
  from tempfile import mkdtemp
  import numpy
  import pytest
  from scipy.cluster import hierarchy
  from scipy.sparse.csgraph import connected_components
  from sklearn.cluster import AgglomerativeClustering, FeatureAgglomeration, ward_tree
  from sklearn.cluster._agglomerative import _TREE_BUILDERS, _fix_connectivity, _hc_cut, linkage_tree
  from sklearn.cluster._hierarchical_fast import average_merge, max_merge, mst_linkage_core
  from sklearn.datasets import make_circles, make_moons
  from sklearn.feature_extraction.image import grid_to_graph
  from sklearn.metrics import DistanceMetric
  from sklearn.metrics.cluster import adjusted_rand_score, normalized_mutual_info_score
  from sklearn.metrics.pairwise import PAIRED_DISTANCES, cosine_distances, manhattan_distances, pairwise_distances
  from sklearn.metrics.tests.test_dist_metrics import METRICS_DEFAULT_PARAMS
  from sklearn.neighbors import kneighbors_graph
  from sklearn.utils._fast_dict import IntFloatDict
  from sklearn.utils._testing import assert_almost_equal, assert_array_almost_equal, assert_array_equal, create_memmap_backed_data, ignore_warnings
  from sklearn.utils.fixes import LIL_CONTAINERS
label_desc: Use image node_id 15 for calling a global function with example usage: test_identical_points() without return types