code: def assert_raises_on_only_one_label(func):
      """Assert message when there is only one label"""
      rng = np.random.RandomState(seed=0)
      with pytest.raises(ValueError, match="Number of labels is"):
          func(rng.rand(10, 2), np.zeros(10))
  
imports: import warnings
  import numpy
  import pytest
  from numpy.testing import assert_allclose
  from scipy.sparse import issparse
  from sklearn import datasets
  from sklearn.metrics import pairwise_distances
  from sklearn.metrics.cluster import calinski_harabasz_score, davies_bouldin_score, silhouette_samples, silhouette_score
  from sklearn.metrics.cluster._unsupervised import _silhouette_reduce
  from sklearn.utils._testing import assert_array_equal
  from sklearn.utils.fixes import CSC_CONTAINERS, CSR_CONTAINERS, DOK_CONTAINERS, LIL_CONTAINERS
label_desc: Use image node_id 11 for calling a global function with example usage: assert_raises_on_only_one_label(func) without return types