code: def test_contour_datetime_axis(split_collections):
      fig = plt.figure()
      fig.subplots_adjust(hspace=0.4, top=0.98, bottom=0.15)
      base = datetime.datetime(2013, 1, 1)
      x = np.array(
          [base + datetime.timedelta(days=d) for d in range(20)]
      )
      y = np.arange(20)
      z1, z2 = np.meshgrid(np.arange(20), np.arange(20))
      z = z1 * z2
      plt.subplot(221)
      plt.contour(x, y, z)
      plt.subplot(222)
      plt.contourf(x, y, z)
      x = np.repeat(x[np.newaxis], 20, axis=0)
      y = np.repeat(y[:, np.newaxis], 20, axis=1)
      plt.subplot(223)
      plt.contour(x, y, z)
      plt.subplot(224)
      plt.contourf(x, y, z)
      for ax in fig.get_axes():
          for label in ax.get_xticklabels():
              label.set_ha("right")
              label.set_rotation(30)
  
      _maybe_split_collections(split_collections)
  
imports: import datetime
  import platform
  import re
  from unittest import mock
  import contourpy
  import numpy
  from numpy.testing import assert_array_almost_equal, assert_array_almost_equal_nulp, assert_array_equal
  import matplotlib
  from matplotlib import pyplot, rc_context, ticker
  from matplotlib.colors import LogNorm, same_color
  import matplotlib.patches
  from matplotlib.testing.decorators import check_figures_equal, image_comparison
  import pytest
label_desc: Use image node_id 13 for calling a global function with example usage: test_contour_datetime_axis(split_collections) without return types