code: def test_ax_elbow():
      clf = KMeans()
      fig, ax = plt.subplots(1, 1)
      out_ax = plot.elbow_curve(X, clf, ax=ax)
      assert ax is out_ax
  
imports: import pytest
  import numpy
  from unittest.mock import Mock
  import matplotlib.pyplot
  from matplotlib.testing.decorators import image_comparison
  from sklearn.tree import DecisionTreeClassifier
  from sklearn.cluster import KMeans, MiniBatchKMeans
  from sklearn.datasets import load_iris
  from sklearn_evaluation import plot
  import sklearn_evaluation.plot.clustering
  from ploomber_core.warnings import PloomberDeprecationWarning
label_desc: Use image node_id 10 for calling a global function with example usage: test_ax_elbow() without return types