code: def test_connectivity_propagation():
      # Check that connectivity in the ward tree is propagated correctly during
      # merging.
      X = np.array(
          [
              (0.014, 0.120),
              (0.014, 0.099),
              (0.014, 0.097),
              (0.017, 0.153),
              (0.017, 0.153),
              (0.018, 0.153),
              (0.018, 0.153),
              (0.018, 0.153),
              (0.018, 0.153),
              (0.018, 0.153),
              (0.018, 0.153),
              (0.018, 0.153),
              (0.018, 0.152),
              (0.018, 0.149),
              (0.018, 0.144),
          ]
      )
      connectivity = kneighbors_graph(X, 10, include_self=False)
      ward = AgglomerativeClustering(
          n_clusters=4, connectivity=connectivity, linkage="ward"
      )
      # If changes are not propagated correctly, fit crashes with an
      # IndexError
      ward.fit(X)
  
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 16 for calling a global function with example usage: test_connectivity_propagation() without return types