code: def test_contourf_symmetric_locator():
      # github issue 7271
      z = np.arange(12).reshape((3, 4))
      locator = plt.MaxNLocator(nbins=4, symmetric=True)
      cs = plt.contourf(z, locator=locator)
      assert_array_almost_equal(cs.levels, np.linspace(-12, 12, 5))
  
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 18 for calling a global function with example usage: test_contourf_symmetric_locator() without return types