code: def test_contour_closed_line_loop(split_collections):
      # github issue 19568.
      z = [[0, 0, 0], [0, 2, 0], [0, 0, 0], [2, 1, 2]]
  
      fig, ax = plt.subplots(figsize=(2, 2))
      ax.contour(z, [0.5], linewidths=[20], alpha=0.7)
      ax.set_xlim(-0.1, 2.1)
      ax.set_ylim(-0.1, 3.1)
  
      _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 27 for calling a global function with example usage: test_contour_closed_line_loop(split_collections) without return types