code: def test_copy(self):
      np.random.seed(0)
      clf = KMeans()
      scikitplot.clustering_factory(clf)
      ax = clf.plot_silhouette(self.X)
      assert not hasattr(clf, "cluster_centers_")
      ax = clf.plot_silhouette(self.X, copy=False)
      assert hasattr(clf, "cluster_centers_")
  
imports: from __future__ import absolute_import
  import unittest
  import scikitplot
  import warnings
  import numpy
  from sklearn.datasets import load_iris
  from sklearn.cluster import KMeans
  import matplotlib.pyplot
label_desc: Use image node_id 3 for calling the TestPlotSilhouette obj's underlying member method code with example usage: obj.test_copy() without return types