code: def test_ax(self):
      np.random.seed(0)
      clf = PCA()
      clf.fit(self.X)
      fig, ax = plt.subplots(1, 1)
      out_ax = skplt.plot_pca_2d_projection(clf, self.X, self.y)
      assert ax is not out_ax
      out_ax = skplt.plot_pca_2d_projection(clf, self.X, self.y, ax=ax)
      assert ax is out_ax
  
imports: from __future__ import absolute_import
  import unittest
  import scikitplot.plotters
  from sklearn.datasets import load_iris
  from sklearn.decomposition import PCA
  import numpy
  import matplotlib.pyplot
label_desc: Use image node_id 3 for calling the TestPlotPCA2DProjection obj's underlying member method code with example usage: obj.test_ax() without return types